lime water experiment class 10

Fun Science Projects & Experiments - Limewater Test

In these lessons, we shall learn the limewater test for carbon dioxide - how it works and how to use it.

Related Pages Alkane And Alkene Tests Science projects, videos and experiments for various grades and topics.

Science Projects or Science Experiments: Grades 5 & 6

The following diagrams show the test for Carbon Dioxide. Carbon Dioxide will turn limewater (calcium hydroxide) cloudy. Scroll down the for examples and explanations.

Limewater Test - To check for carbon dioxide in your breath

Lime Water Breath Experiment Using lime water is a fun and easy way to test for the presence of carbon dioxide. The exhaled carbon dioxide is used to produce a precipitate of calcium carbonate with the lime water.

carbon dioxide + calcium hydroxide (limewater) → calcium carbonate + water

Add 50 ml of lime water to two 100 ml beakers.
Bubble room air through one beaker for one minute using a pipette and pipette pump. Observe and record the results.
With the other beaker, bubble exhaled air through the solution for 1 minute. Try to bubble the air through the same rate that you did with the first beaker. After 1 minute record your results.

Limewater & CO 2 Carbon dioxide dissolves in water to form carbonic acid (H 2 CO 3 ).

Lime water is a solution of calcium hydroxide (Ca(OH) 2 ).

They react to form calcium carbonate (CaCO 3 ) and water. Calcium carbonate is insoluble and forms a white precipitate.

If CO 2 continues to be passed, more carbonic acid forms, which then reacts with the calcium carbonate to form calcium hydrogencarbonate, which is soluble, so the precipitate is seen to dissolve.

To Investigate the Carbon Dioxide Levels of Inhaled and Exhaled Air In this experiment we will investigate the carbon dioxide levels of inhaled and exhaled air. We use limewater to test for the presence of carbon dioxide.

Carbon dioxide dissolves in water Here is some pure water, which has a pH of 7, shown by using this testing paper and matching the color to the chart on the side of the box.

If I take a straw and blow into the water, what gases are going into the water?

The one I am interested in is carbon dioxide, which can dissolve in water and react to form an acid. CO 2 (g) + H 2 O(l) → H 2 CO 3 (aq) → H + (aq) + HCO 3 − (aq)

So after I blow into the water several times, I should have a solution which is more acid than it was before. Let’s check by retesting the pH of the solution. It is now down to 5, rather than the 7 it was as pure water. pH 5 is an acid, so the carbon dioxide has dissolved in the water and reacted.

Thus my chemical reaction really has made hydrogen ions in the water, meaning that the carbon dioxide gas dissolved and reacted.

CO 2 (g) + H 2 O(l) → H + (aq) + HCO 3 − (aq)

What does this mean about rain which passes through air with CO 2 in it?

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Sunday, February 13, 2022

Explain activity 6.4 ncert class 10 science life processes.

In this post, you will learn about activity 6.4 NCERT class 10 science Life Processes which belongs to chapter 6 NCERT solutions. You can also go through activity 6.3 class 10 science life process.

You can learn object, material required, procedure, observation, and conclusion of activity 6.4 NCERT class 10 science life processes.

Activity 6.4

Object – Carbon dioxide is exhaled during respiration

Material Required : Two test tubes, lime water, air pump (small) with rubber tubing, a glass tube.

Procedure : (i) Take freshly prepared lime water in a test tube.

(ii) Blow air from the mouth into this lime water with help of a glass tube.

(iii) Now take the same amount of lime water in another test tube.

(iv) With the help of a small air pump blow air into this lime water. For this fit a rubber tubing at the mouth of the air pump.

Observation : In test tube (B) lime water turns milky within a short period of time. In the second test tube, the lime water remains unaffected.

Inference : Lime water turns milky only when carbon dioxide is mixed with it. Actually, the calcium oxide is converted into white calcium carbonate in the presence of carbon dioxide. Experiment shows that exhaled air contains carbon dioxide and proves that carbon dioxide is produced during respiration. As there is a very little amount of carbon dioxide in the fresh air the lime water didn’t turn milky with its imperiality.

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13. Experiments to demonstrate the release of carbon dioxide through respiration

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MCQ Questions for Class 10 Science Chapter 6 Life Processes

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Class 10 Science Chapter 6 Life Processes MCQs with Answers

Q.1. During respiration exchange of gases take place in (a) trachea and larynx (b) alveoli of lungs (c) alveoli and throat (d) throat and larynx

Q.2. Blood from superior vena cava flows into (a) right atrium (b) right ventricle (c) left atrium (d) left ventricle

Q.3. The green colour of plants is due to the presence of (a) chlorophyll (b) carotene (c) xanthophyll (d) starch

Q.4. The correct sequence of anaerobic reactions in yeast is [NCERT Exemplar]

Q.5. Lipase acts on (a) amino acids (b) fats (c) carbohydrates (d) all of these

Q.6. Blood consist of what fluid medium? (a) Lymph (b) Platelets (c) Plasma (d) All of these

Q.7. In which of the following vertebrate group/groups, heart does not pump oxygenated blood to different parts of the body? [NCERT Exemplar] (a) Pisces and amphibians (b) Amphibians and reptiles (c) Amphibians only (d) Pisces only

Q.8. A student sets up an experiment to study the role of enzymes in digestion of food.

In which test tube, the digestion of protein will occur? (a) Test tubes A as pepsin will breakdown protein into simple molecules. (b) Test tube B as HCl will breakdown protein into simple molecules. (c) Test tube A as pepsin will breakdown into simple molecules. (d) Test tube B as HCl will activate pepsin for breakdown of protein into simple molecules.

Q.9. In which part of the alimentary canal food is finally digested? [NCERT Exemplar] (a) Stomach (b) Mouth cavity (c) Large intestine (d) Small intestine

Q.10. When air is blown from mouth into a test-tube containing lime water, the lime water turned milky due to the presence of [NCERT Exemplar] (a) oxygen (b) carbon dioxide (c) nitrogen (d) water vapour

Q.11. Choose the correct path of urine in our body. [NCERT Exemplar] (a) Kidney →ureter →urethra →urinary bladder (b) Kidney →urinary bladder →urethra →ureter (c) Kidney →ureter →urinary bladder →urethra (d) Urinary bladder →kidney →ureter →urethra

Q.12. The internal (cellular) energy reserve in autotrophs is [NCERT Exemplar] (a) glycogen (b) protein (c) starch (d) fatty acid

Q.13. Which is the correct sequence of parts in human alimentary canal? [NCERT Exemplar] (a) Mouth →stomach →small intestine →oesophagus →large intestine (b) Mouth →oesophagus →stomach →large intestine →small intestine (c) Mouth →stomach →oesophagus →small intestine →large intestine (d) Mouth →oesophagus →stomach →small intestine →large intestine

Q.14. If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected? [NCERT Exemplar] (a) Proteins breaking down into amino acids (b) Starch breaking down into sugars (c) Fats breaking down into fatty acids and glycerol (d) Absorption of vitamins

Q.15. Which is the first enzyme to mix with food in the digestive tract? [NCERT Exemplar] (a) Pepsin (b) Cellulase (c) Amylase (d) Trypsin

Q.16. The image shows the bread moulds on a bread. How these fungi obtain nutrition? (a) By using nutrients from the bread to prepare their own food. (b) By allowing other organisms to grow on the bread and then consuming them. (c) By breaking down the nutrients of bread and then absorbing them. (d) By eating the bread on which it is growing.

Q.17. A student sets up an experiment to study human respiration using lime water, test tube and a straw. Lime water is colourless in the absence of CO2 and is milky in its presence. The student fills a freshly prepared limewater in a test tube and blows air through straw into the limewater. It was observed that the solution turns cloudy as shown. What can be evaluated from this observation?

(a) Oxygen is exhaled during respiration. (b) Water vapours are produced during respiration. (c) Carbon dioxide is exhaled during respiration. (d) Glucose is produced during respiration.

Q.18. A student performs an experiment using a Balsam plant with intact stem, leaves, roots and flowers. The plant was kept in a test tube containing eosin solution (a pink colour dye). The test tube mouth was covered using cotton plug as shown.

The student kept the plant undisturbed in the lab. After 2-3 hours, a transverse section of stem was obtained using sharp scissors and studied under microscope. The studies reveal the presence of pink colour in the vessels of xylem. What does this observation explain? (a) Most portion of the plant stem is occupied by xylem. (b) Water moves through xylem in the plant. (c) Eosin solution gets stored in the xylem. (d) Xylem reacts with eosin and gives colour.

Q.19. A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains [NCERT Exemplar] (a) complex proteins (b) simple proteins (c) fats (d) starch

Q.20. Single circulation, i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by [NCERT Exemplar] (a) Labeo, Chameleon, Salamander (b) Hippocampus, Exocoetus, Anabas (c) Hyla, Rana, Draco (d) Whale, Dolphin, Turtle

Q.21. Lack of oxygen in muscles often leads to cramps among cricketers. This results due to [NCERT Exemplar] (a) conversion of pyruvate to ethanol (b) conversion of pyruvate to glucose (c) non conversion of glucose to pyruvate (d) conversion of pyruvate to lactic acid

Q.22. The opening and closing of the stomatal pore depends upon [NCERT Exemplar] (a) oxygen (b) temperature (c) water in guard cells (d) concentration of CO2 in stomata

Q.23. The inner lining of stomach is protected by one of the following from hydrochloric acid. Choose the correct one. (a) Pepsin (b) Mucus (c) Salivary amylase (d) Bile

Q.24. Rings of cartilage present in the throat ensure that (a) air is filtered (b) air is at room temperature (c) air passage does not collapse (d) air is free of microbes

Q.25. The image shows oxygenated and de-oxygenated blood in the human heart.

What is the direction of deoxygenated blood from right ventricle of the heart? (a) towards the lungs. (b) towards the left atrium of heart. (c) towards the upper body. (d) towards the lower body.

Q.26. Which of the following organisms absorbs nutrition with haustoria? (a) A carnivore (b) A herbivore (c) A parasite (d) A saprophyte

Q.27. The process by which Amoeba obtains food is called (a) phagocytosis (b) assimilation (c) diffusion (d) absorption

Q.28. Which of the following is not a digestive enzyme contained in the pancreatic juice? (i) Lipase (ii) Hydrochloric acid (iii) Mucus (iv) Trypsin (a) (i) and (ii) (b) (i) and (iv) (c) (ii) and (iii) (d) (i) and (iii)

Q.29. The enzymes pepsin and trypsin are secreted respectively by (a) stomach and pancreas (b) salivary gland and stomach (c) liver and pancreas (d) liver and salivary gland

Q.30. Among the following choose the correct option which includes the organisms that have a holozoic mode of nutrition: (a) Plasmodium and Amoeba (b) Parakeet and Amoeba (c) Paramecium and Plasmodium (d) Paramecium and Parasite

Q.31. Raw materials required in the autotrophic mode of nutrition involves: (i) Carbon dioxide and water (ii) Chlorophyll (iii) Nitrogen (iv) Sunlight (a) (i), (ii) and (iii) (b) (i) and (ii) (c) (i), (ii) and (iv) (d) All (i), (ii), (iii) and (iv)

Q.32. The enzymes in pancreatic juice help in the digestion of (a) fats and carbohydrates (b) proteins and fats (c) proteins and carbohydrates (d) proteins, fats and carbohydrates

Q.33. Which of the following help in protecting the inner lining of the stomach from the harmful effect of hydrochloric acid? (a) Mucus (b) Pepsin (c) Trypsin (d) Bile

Q.34. Sometimes we get painful cramps in our leg muscles after running for a long time due to the accumulation of (a) hydrochloric acid (b) fat (c) carbon dioxide (d) lactic acid

Q.35. The vein which brings clean blood from the lungs into the heart is known as (a) pulmonary vein (b) hepatic vein (c) superior vena cava (d) pulmonary artery

Q.36. Movement of the synthesized products from the leaves to the roots and other parts of a plant’s body takes place through the phloem. This process is known as (a) translocation (b) transpiration (c) transportation (d) excretion

Q.37. During deficiency of oxygen in tissues of human beings, pyruvic acid is converted into lactic acid in the [NCERT Exemplar] (a) cytoplasm (b) chloroplast (c) mitochondria (d) golgi body

Q.38. Which among the following procedures is used for cleaning the blood of a person by separating the waste substance from it? (a) Kidney transplant (b) Blood transfusion (c) Dialysis (d) Hydrolysis

Q.39. The excretory unit of the human excretory system is known as (a) nephridia (b) neuron (c) nephron (d) kidneys

Q.40. Plants use the energy stored in ATP to accomplish the process of transportation of (a) water and minerals (b) oxygen (c) water, minerals and food (d) food

Q.41. Which element is used in the synthesis of proteins? (a) Hydrogen (b) Oxygen (c) Nitrogen (d) Carbon dioxide

Q.42. Temporary finger like extensions on Amoeba are called (a) cell membrane (b) cell wall (c) pseudopodia (d) cilia

Q.43. From the given picture of the digestive system, identify the part labelled as gastric gland. (a) A (b) B (c) C (d) D

Q.44. Which among the following is necessary to carry out the blood coagulation in a cut or wound? (a) White blood cells (b) Blood plasma (c) Platelets (d) Red blood cells

Q.45. In which mode of nutrition an organism derives its food from the body of another living organism without killing it? (a) Saprotrophic nutrition (b) Parasitic nutrition (c) Holozoic nutrition (d) Autotrophic nutrition

Q.46. The mode of nutrition found in fungi is (a) parasitic nutrition (b) holozoic nutrition (c) autotrophic nutrition (d) saprotrophic nutrition

Q.47. Roots of the plants absorb water from the soil through the process of (a) diffusion (b) transpiration (c) osmosis (d) none of these

Q.48. The site of photosynthesis in the cells of a leaf is (a) chloroplast (b) mitochondria (c) cytoplasm (d) protoplasm

Q.49. In Amoeba, food is digested in the (a) food vacuole (b) mitochondria (c) pseudopodia (d) chloroplast

Q.50. Which region of the alimentary canal absorbs the digested food? (a) Stomach (b) Small intestine (c) Large intestine (d) Liver

Q.51. The contraction and expansion movement of the walls of the food pipe is called (a) translocation (b) transpiration (c) peristaltic movement (d) digestion

Q.52. The exit of unabsorbed food material is regulated by (a) liver (b) anus (c) small intestine (d) anal sphincter

Q.53. What are the products obtained by anaerobic respiration in plants? (a) Lactic acid + Energy (b) Carbon dioxide + Water + Energy (c) Ethanol + Carbon dioxide + Energy (d) Pyruvate

Q.54. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in (a) cytoplasm (b) mitochondria (c) chloroplast (d) nucleus

Q.55. Glycolysis process occurs in which part of the cell? (a) Cytoplasm (b) Nucleus (c) Mitochondria (d) Chloroplast

Q.56. Name the substances whose build up in the muscles during vigorous physical exercise may cause cramps? (a) Ethanol + Carbon dioxide + Energy (b) Lactic acid + Energy (c) Carbon dioxide + Water + Energy (d) Pyruvate

Q.57. Name the pores in a leaf through which respiratory exchange of gases takes place. (a) Lenticels (b) Vacuoles (c) Xylem (d) Stomata

Q.58. The respiratory pigment in human beings is (a) carotene (b) chlorophyll (c) haemoglobin (d) mitochondria

Q.59. Which plant tissue transports water and minerals from the roots to the leaf? (a) Xylem (b) Phloem (c) Parenchyma (d) Collenchyma

Q.60. A blood vessel which pumps the blood from the heart to the entire body is called (a) artery (b) capillary (c) vein (d) haemoglobin

Q.61. Name a circulatory fluid in the human body other than blood. (a) Platelets (b) RBC (c) Lymph (d) Plasma

Q.62. Which part of nephron allows the selective reabsorption of useful substances like glucose, amino acids, salts and water into the blood capillaries? (a) Tubule (b) Glomerulus (c) Bowman’s capsule (d) Ureter

Q.63. Where is the dirty blood in our body filtered? (a) Heart (b) Lungs (c) Ureter (d) Kidneys

Q.64. Autotrophic organisms include (a) bacteria and virus (b) bacteria and fungi (c) green plants and some bacteria (d) green plants and all bacteria

Q.65.Which of the following are chiefly digested in the stomach? (a) Carbohydrates (b) Proteins (c) Lipids (d) Fats

Q.66. Large intestine in man mainly carries out (a) absorption of water (b) assimilation (c) digestion of fats (d) digestion of carbohydrates

Q.67. The part of the digestive system where no digestion takes place is (a) ileum (b) stomach (c) mouth (d) oesophagus

Q.68. Arteries and veins are connected by a network of extremely narrow tubes called (a) sieve tubes (b) capillaries (c) vena cava (d) valves

Q.69. Which of the following are energy foods? (a) Carbohydrates and fats (b) Proteins and mineral salts (c) Vitamins and minerals (d) Water and roughage

Q.70. The fermentation of glucose by yeast normally yields (a) alcohol, CO2 and 36 ATP (b) CO2, H2O and 36 ATP (c) alcohol, CO2 and 2 ATP (d) lactic acid, CO2 and 2 ATP

Q.71. A large quantity of one of the following is removed from our body by lungs? (a) CO2 and H2O (b) CO2 only (c) H2O only (d) Ammonia

Q.72. In respiration, air passes through (a) Pharynx → nasal cavity → larynx → trachea bronchi → bronchioles (b) Nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles (c) Larynx → nasal cavity → pharynx → trachea (d) Larynx → pharynx → trachea → lungs

Q.73. A biochemical compound that readily combines with oxygen and distributes it throughout the human body is (a) water (b) urea (c) haemoglobin (d) acetylcholine

Q.74. The process in which loss of water takes place in the form of water vapour through stomata is called (a) transportation (b) transpiration (c) guttation (d) translocation

Q.75. In a closed circulatory system, blood is completely enclosed within (a) vessels (b) heart (c) skeleton (d) sinuses

Q.76. Normal blood pressure (systolic/diastolic) is (a) 120/80 mm of Hg (b) 160/80 mm of Hg (c) 120 60 mm of Hg (d) 180/80 mm of Hg

Q.77. Blood pressure is measured by an instrument called (a) barometer (b) sphygmomanometer (c) photometer (d) manometer

Q.78. Which of the following statements is not correct? (a) Deoxygenated blood is poured into right atrium of heart. (b) The excretory units of flatworms are flame cells. (c) Human kidney has about 1 million nephridia. (d) Tracheids and vessels are non-living conducting tissues.

Q.79. The chlorophyll in photosynthesis is used for (a) absorbing light (b) breaking down water molecule (c) no function (d) reduction of CO2

Q.80. Proteins after digestion are converted into (a) carbohydrates (b) small globules (c) amino acids (d) starch

Q.81. Carbohydrates in the plants are stored in the form of (a) glycogen (b) starch (c) glucose (d) maltose

Q.82. Opening and closing of pores is a function performed by (a) stomata (b) chlorophyll (c) chloroplast (d) guard cells

Q.83. Bile juice is secreted by (a) stomach (b) pancreas (c) small intestine (d) liver

Q.84. Which of these juices is secreted by pancreas? (a) Trypsin (b) Pepsin (c) Bile juice (d) Both (a) and (b)

Q.85. Name the tube which connects the kidneys to the urinary bladder. (a) Urethra (b) Nephron (c) Tubule (d) Ureter

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Activity 6.5 NCERT class 10 science chapter 6 Life processes

Table of Contents

Brief procedure: Activity 6.5 asks us to pass the air produced by yeast on sugar solution or fruit juice into lime water.

Explanation: Yeast is a unicellular bacteria. It lives on organic food like sugar, flour etc. Yeast breaks down food material and releases carbon dioxide through the process called Fermentation . When this air pass through the bent tube It makes lime water milky.

Ca(OH) 2 (aq) + CO 2 (g) ——–> CaCO 3 (s)

(Lime) (Insoluble milky Precipitate)

This experiment shows that yeast lives on fruit juices, sugar and produces carbon dioxide.

Application:

You must have seen people who use yeast powder in making a base for pizza or bread. They first put yeast in a warm sugar solution. Warm temperature and sugar are favourable conditions to the yeast cells. Yeast cells multiply and produce carbon dioxide which raises the dough and makes it spongy. To know more you can read an article ‘ Science of bread ‘ by exploratorium.edu.

Next: Why fishes breath faster. Activity 6.6.

Experiment to demonstrate our lung exhales carbon dioxide: Activity 6.4.

7 thoughts on “Activity 6.5 NCERT class 10 science chapter 6 Life processes”

As carbon dioxide is the only product as in gases soo this happens instantly….

U left one question unanswered . how long the reaction takes place ?

What you say about this site , can you tell me how

This site is very useful and its help in achieving good marks In board exam.

Its very easy and also with full of concepts. With your approach towards NCERT activities we students can face application based questions. Hats off from me.

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Limewater Carbon Dioxide Test

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6. Life Processes | Class 10 CBSE | Web Notes | Part 3 | Respiration

6. life processes.

RESPIRATION

Experiment to prove release of CO 2 during respiration in human

Take some freshly prepared lime water in 2 test tubes.
In one, blow air through lime water. It immediately turns lime water milky.
In other test tube, pass air using a syringe or pichkari . It takes much time to turn the lime water milky.
It shows that the breath-out air contains more CO 2 as compared to atmospheric air.

Experiment to prove release of CO 2 during respiration in Yeast

Add some yeast to fruit juice or sugar solution. Take this mixture in a test tube fitted with a one-holed cork.
Fit the cork with a bent glass tube. Dip its free end into a test tube containing freshly prepared lime water.
Air taken out through the tube makes lime water milky. It is due to the production of CO 2 in the mixture of yeast & sugar solution. Here, fermentation occurs.

In yeast, the pyruvate is converted into ethanol & CO 2 . It occurs during fermentation.
Sometimes, when there is no oxygen in our muscle cells, the pyruvate breaks down into lactic acid (3-carbon). This build-up of lactic acid in muscles during sudden activity causes cramps.

Gas exchange in plants:

It occurs through stomata. Here, CO 2 & oxygen are exchanged by diffusion. The large intercellular spaces in leaves help the cells in contact with air.

During day, CO 2 formed by respiration is used for photosynthesis. So, CO 2 is not released but oxygen is released. At night, photosynthesis does not occur. So, CO 2 is released out but oxygen is not released.

Gas exchange in animals:

Aquatic animals breathe dissolved oxygen in water.

In fishes, the respiratory organ is gills with gill slits behind their eyes . They may be covered by operculum.

During breathing, fishes open and close mouth & gill slits (or operculum) in a coordinated manner and timing. They take in water through mouth and pumps over the gills. From the gills, dissolved O 2 is taken up by blood.

The amount of dissolved O 2 is lower than that in the air. So, the rate of breathing in aquatic organisms is faster than that in terrestrial organisms.

In terrestrial animals, there are different types of organs to breathe atmospheric oxygen. They increase surface area which is in contact with the atmosphere.

Surface of respiratory organs is very fine and delicate for easy gas exchange. To protect this surface, it is placed within the body. So, some passages are necessary to carry air in and out of respiratory organ.

Human respiratory system

Tobacco or tobacco products affect tongue, lungs, heart and liver. Smokeless tobacco also causes heart attacks, strokes, pulmonary diseases & cancers. Oral cancer is highly reported in India due to tobacco chewing in the form of gutkha. Smoking destroys cilia on the upper respiratory tract. As a result, germs, dust, smoke etc. enter lungs and cause infection, cough & lung cancer (common cause of death).

- If the alveolar surface were spread out, it would cover about 80 m 2 . The surface area of human body is about 1.9 m 2 .

- If diffusion were to move oxygen in our body, it would take 3 years for an oxygen molecule to get to toes from our lungs. Haemoglobin helps in faster gas transport.

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👉 part 1: what are life processes 👉 part 2: nutrition 👉 part 3: respiration, 👉 part 4: transportation 👉 part 5: excretion.

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Science project, the limewater carbon dioxide test.

Carbon dioxide , also commonly known by its chemical formula CO 2 , is one of the major building blocks of life. It is usually found in its gaseous form, and is a major part of the plant and animal life cycle. CO 2 is consumed by plants in photosynthesis and is produced by animals (like us!) during respiration. It is also expelled from the earth’s core during volcanic eruptions and exits a vehicle’s engine from its tailpipe when the motor is running. It’s considered a greenhouse gas, one of several compounds which contributes to global climate change. Carbon dioxide is all around us, and this simple experiment will help you see CO 2 production by conducting a carbon dioxide test with two chemical reactions.

How can we test for the presence of carbon dioxide?

Container with lid (a plastic food container would work fine)
Distilled water
Calcium oxide (lime)
¼ cup measuring cup
White vinegar
Small shallow dish (a baby food jar or a salad dressing cup work great)
2 clear water bottles
Modeling clay
2 bendy straws
Toilet paper
Baking soda
Take the container with a lid and add 1L of distilled water and 1 teaspoon of calcium oxide. Stir with the spoon.
Let the solution sit overnight. This will be your limewater. Why do we refer to it as limewater?
Fill the small, shallow dish with limewater.
Take modeling clay and mold it into a ring just below the bendable part of your straw.
Add ¼ cup of water and ¼ cup of white vinegar into the water bottle.
Take 1 square of toilet paper and spread some baking soda in the middle of the paper. Roll it up and twist the ends of the toilet paper so the baking soda does not spill out.
Drop of the baking soda in the toilet paper into the water bottle.
Immediately insert the end of the straw into the water bottle, making sure that it is submerged in the liquid. Use the modeling clay to seal the straw into the neck of water bottle.
Bend the end of the straw and submerge it in your container of limewater.
Observe what happens. Record your observations.
Add ¼-cup of limewater to another clear water bottle.
Make a second modeling clay plug around your second bendy straw and insert the straw and plug into the water bottle.
Take a deep breath and exhale into the straw so your breath goes into the limewater. Be careful not to suck any lime water up!
Record your observations.

When carbon dioxide, CO 2 , enters the limewater, the limewater becomes cloudy. When you exhale into the bottle, the limewater will turn cloudy.

Chemists refer to baking soda as sodium bicarbonate , a compound with the chemical formula NaHCO 3 . Vinegar is a mixture of acetic acid (CH 3 COOH) and water (H 2 0). When the two are combined, the following reaction takes place:

NaHCO 3 + HC 2 H 3 O 2 → NaC 2 H 3 O 2 + H 2 O + CO 2

But this is known to happen in two steps:

NaHCO 3 + HC 2 H 3 O 2 → NaC 2 H 3 O 2 + H 2 CO 3,

...where carbonic acid is formed, and finally

H 2 CO 3 → H 2 O + CO 2,

...where carbonic acid breaks down into water and CO 2 . The CO 2 then bubbles up through the straw and into the limewater.

Limewater is created with calcium hydroxide , or Ca(OH) 2 . Named for the mineral, not the fruit, lime reacts with CO 2 in water to form calcium carbonate , which is white and does not dissolve in water, causing the water to turn cloudy.

Similarly, when we exhale we are removing CO 2 from our bodies, so breathing CO 2 into the lime water will produce the same reaction, though probably not as quickly due to the smaller amount of CO 2 in your breath.

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Science Projects > Chemistry Projects > How to Make Limewater

How to Make Limewater

Limewater is used in many science experiments and is easy to make on your own.

What is Limewater?

Limewater comes in two varieties. The first is natural. It’s water that contains a higher-than-normal amount of calcium carbonate or calcium sulfate. The second variety is manmade: “milk of lime.” It’s a solution made from lime, acted upon (or slaked ) by water. Lime itself is a solid, white compound of calcium and oxygen. It’s made from burning limestone (a “stone” made mostly of calcite), shells, and bones.

What’s It Good For?

Limewater is used most often to extract impurities from sugar made from (sugar) beets.

It’s also used to make soft water from hard water.

Limewater is also a neutralizing agent; it makes everything from corn flour to wastewater beneficial or safer.

It can also be used to bleach products, everything from stone to human hair.

Finally, limewater can be used to supplement coral reef production.

How to Make the Solution

1. Put 1 teaspoon of calcium hydroxide in a clean glass jar, up to 1 gallon in size. (Limewater is a saturated solution, which means there will be some extra chemical that doesn’t dissolve. A teaspoon will result in a fully saturated solution whether you use a gallon jar or a smaller one.)

2. Fill the jar with distilled or tap water.

3. Shake the jar vigorously for 1-2 minutes, then let it stand for 24 hours.

4. Being careful not to stir up the sediment, pour the clearer solution off the top of the jar through a clean coffee filter or filter paper .

5. Repeat the filtering step, if necessary, to obtain a clear limewater solution. Store in a clean jar or bottle.

When carbon dioxide is bubbled into limewater, calcium carbonate (CaCO 3 ) is produced. It precipitates out as a white suspended solid, making the solution appear cloudy.

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Chemistry Practicals
CBSE Class 10 Chemistry Practical
Types Of Reactions Experiment

Types of Reactions - Combination, Decomposition, Displacement, Double displacement

Types of reactions.

In this article, we have discussed step by step procedure to perform CBSE Class 10 Science Practicals experiment Types of Reactions. It will help you understand the different types of reactions viz combination, displacement, decomposition, double displacement reaction on the following actions – water on quicklime, iron nails in CuSO 4 , heat on FeSO 4 , a reaction between NaSO 4 and BaCl 2 .

Combination Decomposition Displacement Double Displacement

Experiment 3(A) – Combination

Materials required.

Quick lime (Calcium oxide)
Borosil beaker
Distilled water
Litmus paper strips

When calcium oxide is mixed in water it dissolves and forms calcium hydroxide (basic in nature). During this reaction, a lot of heat is liberated and therefore, it is called an exothermic reaction. The equation is as follows:

CaO(s) + H 2 O(l) → Ca(OH) 2 (aq) + Heat ………(1)

Due to the basic nature of calcium hydroxide, it turns red litmus paper blue in colour. When carbon dioxide gas is passed through the calcium hydroxide the solution turns milky white.

Ca(OH) 2 (aq) + CO 2 → CaCO 3 + H 2 O

In the reaction (1) slaked lime is formed by combining two products viz, quick lime and water. Therefore, when two or more than two substances combine to give a single product it is termed as combination reaction. The reactions accompanied by the evolution of heat are called exothermic reactions.

Wash a borosil beaker with distilled water and dry it.
Take a small amount of calcium oxide (quick lime) and slowly add water to it.
Wash and take a clean glass rod to stir the mixture of quick lime and water.
Touch the beaker carefully from outside.
Observe the change.
With the help of dropper take a few drops of the mixture from the beaker and place it on red and blue litmus paper strips.
Wait and observe.

Observation

Experiment	Observation
Mixture in beaker	A hissing sound is heard during the reaction when water is added to the beaker containing quick lime. Due to the evolution of heat during the reaction the temperature increases and makes the solution hot.
Solution on litmus paper	Drops on the red litmus paper strip change the colour of the paper to blue whereas there is no colour change observed on the blue litmus paper.

Result and Conclusion

From the above experiment we can conclude that the reaction occurred between calcium oxide (Quick lime) and water combine to produce one single product slaked lime (Ca(OH) 2 ) is called combination reaction as well as an exothermic reaction.

Precautions to be taken during the Experiment

Take a small amount of compound such as quick lime to perform the experiment.
Since the reaction is exothermic avoid touching the mixture directly.
Carefully pour water into the borosil beaker containing calcium oxide (quick lime).
Calcium oxide causes severe burns and therefore it should be handled with a spatula.
Use good quality glass beaker during the experiment because if the beaker is of poor quality then there are chances of crack on the beaker due to the exothermic reaction.

1. Quick lime is also known as _________.

Ans: Calcium oxide (CaO).

2. What type of reaction takes place between quicklime and water?

Ans: Combination reaction.

3. What is the name of the product that is obtained after the combination reaction?

Ans: Slaked lime (Ca(OH) 2 )

4. Combination reaction that takes place between quicklime and water is also known as _______.

Ans: Exothermic reaction.

5. How to prepare lime water?

Ans: It is a mixture of calcium oxide and water.

Experiment 3(B) – Decomposition

Ferrous sulphate crystals
Test tube holder
Boiling tube
Bunsen burner
Safety glass

Ferrous sulphate crystals are ferrous sulphate heptahydrate with a chemical formula FeSO 4 .7H 2 O and are green in colour.

On heating the ferrous sulphate heptahydrate it loses seven water molecules to form anhydrous ferrous sulphate (FeSO 4 ) and is white in colour. The reaction is as follows:

FeSO 4 .7H 2 O → FeSO 4 (s) + 7H 2 O ………….(1)

(Green colour) (white colour)

Ferrous sulphate when heated is decomposed to ferric oxide, sulphur trioxide, and sulphur dioxide. The reaction is as follows:

FeSO 4 (s) → Fe 2 O 3 (s) + SO 2 (g) + SO 3 (g) ………….(2)

(White colour) (brown colour) (colourless) (colourless)

In the reaction (2) one substance FeSO 4 (Ferrous sulphate) splits into three substances ferric oxide (Fe 2 O 3 ), sulphur dioxide (SO 2 ), and sulphur trioxide (SO 3 ) due to heat. Therefore, this reaction is called decomposition reaction or also known as a thermal decomposition reaction.

We can combine reaction (1) and (2) and write it as follows:

2FeSO 4 .7H 2 O(s) → Fe 2 O 3 (s) + SO 2 (g) + SO 3 (g) + 14H 2 O(g)

Wash a boiling tube with distilled water and dry it.
Take 2 grams of ferrous sulphate crystals in the tube.
Make a note of the colour of the crystals.
Use a test tube holder to hold the boiling tube.
Heat the boiling tube on the bunsen burner as shown in the figure.
Observe the colour of the residue got and smell the odour of the gases evolved.
Tiny colourless water droplets are seen near the neck of the tube.
Gently turn it towards your nose and smell for any gas evolved.
Wet blue and red litmus paper strips.
Hold the litmus paper strips near the mouth of the boiling tube.
Observe the change
Classify the type of reaction.

Experiment	Observation
Boiling tube test
Litmus paper test

From the above experiment 3 (B) we can conclude that the reaction occurred on heating ferrous sulphate crystals is decomposition reaction which decomposes to produce Fe 2 O 3 , SO 2 , and SO 3 . Since this decomposition reaction is carried out by heating it is also known as a thermal decomposition reaction .

Do not keep the mouth of the boiling tube towards yourself.
Do not smell the gas by directly getting it under your nose but gently turn it towards your nose and blow it with your hand.
Wearing safety glasses is important while you are performing this experiment.
Thoroughly wash the boiling tube with distilled water and dry it before using it.
Use good quality boiling tube while heating the ferrous sulphate crystals.
Take care to keep the sulphur dioxide and sulphur trioxide gas coming in contact with your eyes as they cause irritation to eyes.

1. Can you write the formula of ferrous sulphate crystals?

Ans: FeSO 4 .7H 2 O.

2. Ferrous sulphate crystals are also called ______.

Ans: Green vitriol.

3. Name the two gases evolved during the decomposition reaction.

Ans: Sulphur dioxide and sulphur trioxide.

4. What is the colour of the residue left in the boiling tube after the decomposition reaction?

Ans: Brown.

5. Decomposition reaction is also known as ______.

Ans: Thermal decomposition reaction.

Experiment 3(C) – Displacement

Test tube stand
Two test tubes
Two iron nails
Measuring cylinder
Copper sulphate solution
Laboratory stand with clamp

As per the reactivity series, the more reactive metals displace the less reactive metals. When iron is compared with copper, it is placed above copper in activity series. Therefore the metals placed above are more reactive whereas the metals placed below are less reactive.

When iron nails are placed in CuSO 4 iron displaces copper from copper sulphate to form ferrous sulphate. The iron nails get deposited with a brownish red substance of the copper metal. The reaction is as follows:

Fe(s) + CuSO 4 (aq) → FeSO 4 (aq) + Cu(s)

Metallic iron displaces copper ion (Cu 2+ ) from its salt is an example of a chemical displacement reaction. Metallic iron is converted to ferrous iron, the cupric ion is converted to metallic copper. The reaction is as follows:

Fe(s) + Cu 2+ (aq) → Fe 2+ (aq) +Cu(s)

Experimental Setup:

Wash two test tubes with distilled water and dry them.
Label the test tube as P and Q.
Add 20mL of distilled water in the test tube and mix copper sulphate crystals in P.
Transfer 10Ml of solution from P to Q.
Take two iron nails by cleaning them with sandpaper.
Take one iron nail and dip it in the CuSO 4 in test tube P for 15 minutes.
Take another iron nail and dip it in the CuSO 4 in test tube Q for 15 minutes.
Observe the intensity of the blue colour of CuSO 4 before and after the experiment performed in test tube P and Q.
Record your results.

Experiment	Before Experiment	After Experiment
Colour of CuSo	Blue	Green
Colour of iron nail	Silvery grey	Brownish red coating

From the above experiment 3 (C) we can conclude that the reaction occurred when iron nails were dipped in the copper sulphate solution for 15 minutes the colour of the solution changes to green and brownish red copper metal is deposited on the nail. Therefore this is a displacement reaction .

Clean the iron nails by sandpaper before dipping them in a copper sulphate solution.
Make dilute CuSO 4 for the experiment otherwise, the colour change will not be seen in its concentrated form.
Use good quality boiling tube.

1. When iron nails are dipped in the copper sulphate solution the colour of the solution changes. Why?

Ans: Copper is less reactive when compared to iron. Therefore iron has the ability to displace it from its salt solution.

2. What is the basic principle of this experiment?

Ans: More reactive metals displace less reactive metals.

3. What is the cause for displacement reaction?

Ans: Difference in reactivities of metals causes displacement reaction.

4. Can you name the metal that deposits reddish brown substance on the iron nails when dipped in CuSO 4 ?

Ans: Copper metal.

5. What do you mean by reactivity series of metals?

Ans: Metals arranged in the decreasing order of their reactivities.

Experiment 3(D) – Double Displacement

Conical flask
Barium chloride solution
Sodium sulphate solution

Reactions occurring in the solution by exchanging ionic compounds to form new compounds are called double displacement reactions. The ionic compounds considered as reactants are water soluble. One of the products is formed as a precipitate or as a gas which is water soluble.

When two solutions viz sodium sulphate and barium chloride are mixed, double displacement reaction as below occurs.

Na 2 SO 4 (aq) + BaCl 2 (aq) → BaSO 4 (s) + 2NaCl(s)

Sulphate ions from the solution of sodium sulphate are displaced by chloride ions and the chloride ions from the solution of barium chloride are displaced by sulphate ions.

Take two test tubes, wash them with distilled water and dry them.
Pour 5mL of barium chloride in the test tube P and observe the colour.
Pour 5mL of sodium sulphate in the test tube Q and observe the colour.
Take a conical flask and pour the solutions from both the test tube into it.
Stir the mixture added to the conical flask with a glass rod.
Keep it undisturbed for some time.
Observe the change in colour of the solution.
Record your results in the below-given table.

Experiment	Observation
Colour of test tube P and test tube Q	Colourless
Mixture of solution in conical flask	Precipitation is formed

From the above experiment 3 (D) we can conclude that the reaction occurred on mixing the solutions of barium chloride and sodium sulphate produce a white precipitate compound by exchanging their ions. This reaction is known as a double displacement reaction.

The test tube, glass rod, and conical flask should be washed with distilled water and dried before the experiment.
The volume of sodium sulphate and barium chloride should be equal.
Do not try to taste or touch the chemicals.
While combining the solutions in the mixture pour sodium sulphate first and then slowly add barium chloride to it.

1. Barium sulphate is soluble in water. True or false?

2. Sodium sulphate and barium chloride are ionic compounds. True or false?

3. The reaction between sodium sulphate and barium chloride is called a double displacement reaction. Why?

Ans: It is because they exchange their ions.

4. Can you define double displacement reaction?

Ans: The reactions where two compounds exchange their salts to form an insoluble compound.

5. What happens when you mix sodium sulphate with barium chloride?

Ans: A white precipitate is formed.

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

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Photosynthesis

Class 10 - selina concise biology solutions, progress check 1.

Answer the following in "Yes" or "No"

(i) All parts of a green plant carry out photosynthesis.

(ii) All green parts of a plant carry out photosynthesis.

(iii) Photosynthesis is the only biological process that releases oxygen into the air.

(iv) Out of nine types of chlorophylls, chlorophyll a and b are the most abundant.

(v) Too much light destroys chlorophyll.

(vi) No transpiration occurs during photosynthesis.

(vii) During sunlight, the guard cells turn flaccid to open the stomata.

(i) No Corrected Statement — A few parts of a green plant like roots and flowers does not carry out photosynthesis as they lack chloroplasts and chlorophyll.

(vi) No Corrected Statement — Photosynthesis and transpiration go on side by side.

(vii) No Corrected Statement — During sunlight, the guard cells turn turgid to open the stomata.

Progress Check 2

Write the overall summary of the chemical equation of photosynthesis.

6 CO 2 + 12 H 2 O → chlorophyll light energy C 6 H 12 O 6 + 6 H 2 O + 6 O 2 ↑ 6\text{CO}_2 + 12\text{H}_2\text{O} \xrightarrow[\text{chlorophyll}]{\text{light energy}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{H}_2\text{O} + 6\text{O}_2 \uparrow 6 CO 2 + 12 H 2 O light energy chlorophyll C 6 H 12 O 6 + 6 H 2 O + 6 O 2 ↑

Which single substance in the above equation is repeated in raw material as well as reproduced as an end product?

What is the source of oxygen released in photosynthesis — CO 2 or H 2 O ?

What happens in photolysis?

The energy of Sun absorbed is used in splitting the water molecule into its two components (Hydrogen and Oxygen) and releasing electrons. This process is termed as photolysis.

Dark reaction involves utilisation of CO 2 in producing C 6 H 12 O 6 (glucose). Why is this phase called dark reaction ?

The given reaction does not require light. It can occur during day as well as night. Therefore, it is known as Dark reaction.

Glucose produced during photosynthesis is soon polymerised into starch. What does polymerisation mean?

The process of conversion of many simpler molecules into a complex, bigger molecule is termed as polymerisation. Several molecules of glucose join together to form a starch molecule.

Why is it better to call the dark phase of photosynthesis as "light-independent phase"?

The old term 'dark-phase' did not mean that it occurs when it is dark i.e. night. It only means that the reactions are not dependent on light. That is why, it is now better called as "light-independent phase".

Progress Check 3

How do the following favour increased photosynthesis?

(i) Large surface area of the leaf.

(ii) Thinness of the leaf.

(iii) More numerous stomata.

(i) Large surface area of the leaf enables maximum light absorption by plant. Increased absorption of solar energy increases the Photosynthesis.

(ii) Thinness of the leaf reduces the distance between cells facilitating rapid transport of raw materials and translocation of food.

(iii) More numerous stomata allow rapid gaseous exchange and speed up the process of photosynthesis.

Name the three end-products of photosynthesis and mention the fate of each of them in the plant.

The three end products of photosynthesis are:

immediately consumed by the plant cells
stored in the form of insoluble starch
converted into sucrose
used in synthesizing fats, proteins,etc.
Water — can be reutilized in continuance of photosynthesis.
Oxygen — It is used in respiration in the leaf cells. Extra oxygen is released and diffused out in atmosphere.

If we keep on increasing CO 2 concentration in the air, will the rate of photosynthesis also keep on increasing in direct proportion? Yes/No. Explain.

Increasing carbon dioxide concentration increases rate of photosynthesis but it is stabilised at a particular point (upto 0.02% of CO 2 ) if there is no change in light intensity. If the light intensity is increased then increase in carbon dioxide concentration further increases the rate of photosynthesis and is again stabilised at 0.05% of CO 2 .

Progress Check 4

Why is it necessary to destarch the leaves of a plant before performing an experiment on photosynthesis?

In any experiment on photosynthesis, the presence of starch shows that the process of photosynthesis occurred. Therefore it is necessary to remove any pre-existing starch from the leaves. For destarching, the plant is kept for 24-48 hours in dark. It stops the synthesis of starch and the pre-existing starch, by then, is removed from leaves and is stored in storage organs.

Why do we perform the iodine test ?

We perform the iodine test to test the presence of starch.

What chemical do you use to remove CO 2 from inside a flask in certain experiments on photosynthesis ?

Potassium hydroxide

All food chains start with a plant. Why is this so?

The plants are called producers. They are the only organism with ability to convert the solar energy into chemical energy of the food. Therefore, all food chains start with a plant.

The honey bee produces honey. In terms of the food chain, is the honey bee a producer or a consumer?

In terms of food chain, the honey bee is a consumer as it consumes plant nectar and derive its energy from nectar to carry out all the physiological processes. Honey produced by it is derived indirectly from plants. Therefore, Honey bee cannot be called as a producer.

Multiple Choice Type

Chlorophyll is located in :

Reason — Chlorophyll is located in the walls of thylakoid.

Which of the following is not applicable to the process of photosynthesis ?

Oxygen is evolved
Carbon dioxide is absorbed

Carbon dioxide is evolved

Water is utilized

Reason — In the process of photosynthesis, carbon dioxide is absorbed and oxygen is evolved as a by-product.

The colour of VIBGYOR spectrum which is reflected by chlorophyll is:

Reason — The colour of any object is the light that is reflected by it. The chlorophyll reflects green colour and therefore it is green to our eyes.

The basic functional unit of solar energy which is absorbed by the pigment chlorophyll is:

Phytochrome

Reason — The basic functional unit of solar energy is photon that is absorbed by the chlorophyll molecules and this leads to start of chain of reactions of photosynthesis.

The molecules of water split during:

Photorespiration
Phosphorylation
Photophosphorylation

Reason — The chlorophyll molecule absorbs solar energy and this energy is used to split the water molecule. This process ia called photolysis. (photo means light, lysis means disintegration)

The granum is a pile of many :

Reason — Stacked thylakoids are known as granum.

Which of the following is used to remove chlorophyll from the leaves:

Iodine solution

Methylated spirit

Reason — The leaf is boiled in Methylated spirit to remove chlorophyll.

The raw material which is reduced during photosynthesis is :

Carbon dioxide

Reason — Carbon dioxide loses its oxygen or is reduced to form glucose. (loss of oxygen is reduction)

The optimum temperature for the process of photosynthesis is :

Reason — The rate of photosynthesis is maximum at 35°C and falls beyond it.

Question 10

Conversion of several glucose molecules into starch is termed as :

Polymerisation

Reason — Polymerisation is the process by which simple monomers (glucose) join to form complex polymers (starch).

Very Short Answer Type

Name the following:

(a) The category of organisms that prepare their own food from basic raw materials.

(b) The kind of plastids found in the mesophyll cells of the leaf.

(d) The first form of food substance produced during photosynthesis.

(e) The source of CO 2 for aquatic plants.

(f) The part of chloroplast where the dark reaction of photosynthesis takes place.

(a) Autotrophs.

(b) Chloroplasts.

(d) Glucose.

(e) The carbon dioxide dissolved in water.

(f) Stroma.

Given below are groups of terms. In each group, the first pair indicates the relationship between the two terms. Complete the second pair accordingly.

(a) Chlorophyll : Magnesium :: Haemoglobin : ............... .

(b) Light reaction : Granum :: Dark reaction : ............... .

(d) Respiration : Carbon dioxide :: Photosynthesis : ............... .

(e) Water and minerals : Xylem :: Prepared food : ............... .

(a) Chlorophyll : Magnesium :: Haemoglobin : Iron

(b) Light reaction : Granum :: Dark reaction : Stroma

(d) Respiration : Carbon dioxide :: Photosynthesis : Oxygen

(e) Water and minerals : Xylem :: Prepared food : Phloem

Short Answer Type

Identify the false statements and rewrite them correctly by changing the first or last word only.

(a) Dark reaction of photosynthesis occurs during night time.

(b) Photosynthesis requires enzymes.

(d) Photosynthesis results in loss of dry weight of the plants.

(e) Photosynthesis stops at a temperature of about 35°C.

(f) Photosynthesis occurs only in cells containing chloroplasts.

(g) Green plants perform photosynthesis.

(h) Algae are autotrophs.

(a) False Corrected statement — Dark reaction of photosynthesis occurs simultaneously with light reaction.

(d) False Corrected statement — Respiration results in loss of dry weight of the plants.

(e) False Corrected statement — Photosynthesis stops at a temperature of about 40°C.

Fill in the blanks with the appropriate answer from the choices given in the brackets.

(a) The site of light reaction in the cells of a leaf is ............... (cytoplasm, stroma, grana).

(b) The chemical substance used to test the presence of starch in the cell of a leaf is ............... (CaCl 2 , iodine solution, Benedict solution).

(d) The dark reaction of photosynthesis is known as ............... (Hill reaction, cyclic phosphorylation, Calvin cycle).

(e) In the flowering plants, food is transported in the form of ............... (sucrose, glucose, starch).

(a) The site of light reaction in the cells of a leaf is grana .

(b) The chemical substance used to test the presence of starch in the cell of a leaf is iodine solution .

(d) The dark reaction of photosynthesis is known as Calvin cycle .

(e) In the flowering plants, food is transported in the form of Sucrose .

Are the following statements true or false ? Give reason in support of your answer.

(a) The rate of photosynthesis continues to rise as long as the intensity of light rises.

(b) The outside atmospheric temperature has no effect on the rate of photosynthesis.

(d) Destarching of the leaves of a potted plant can occur only at night.

(e) If a plant is kept in bright light all the 24 hours for a few days, the dark reaction (biosynthetic phase) will fail to occur.

(f) Photosynthesis is considered as a process supporting all life on earth.

(a) False Corrected statement — Photosynthesis increases with the light intensity up to a certain limit only, and then it gets stabilised at the point S'(0.02% CO 2 ).

(b) False Corrected statement — The atmospheric temperature is an important external factor affecting photosynthesis. With the rise in temperature, the rate of photosynthesis rises. This rise occurs up to the optimum temperature of 35°C (maximum suitable temperature when the photosynthesis occurs best) after which the rate falls and stops above 40°C.

(c) False Corrected statement — Ice cold water will hamper the process of photosynthesis in the immersed leaf, even if there is sufficient sunshine because the temperature is an important factor for the rate of photosynthesis.

(d) False Corrected statement — For destarching, the potted plant can be kept in a dark room for 24-48 hours. During this period, all the starch will be removed from the leaves and stored in the storage organs.

(e) False Corrected statement — If a plant is kept in bright light all the 24 hours for a few days, the dark reaction (biosynthetic phase) will continue to occur because the dark reaction is independent of light and it occurs simultaneously with the light dependent reaction.

Given below are five terms. Rewrite the terms in the correct order so as to be in logical sequence with regard to photosynthesis: (i) water molecules, (ii) oxygen, (iii) grana, (iv) hydrogen and hydroxyl ions, (v) photons.

Photons, grana, water molecules, hydrogen and hydroxyl ions, oxygen.

State any four differences between photosynthesis and respiration.

Photosynthesis	Respiration
Photosynthesis utilizes carbon dioxide and water in the presence of light to produce glucose and oxygen.	Respiration uses oxygen and glucose to power the activities of the cell.
Photosynthesis results in gain of dry weight of the plants.	Respiration results in loss of dry weight of the plants.
The raw materials for the photosynthesis are water, carbon dioxide and sunlight.	The raw material for respiration is glucose.
Photosynthesis occurs in plants and some photosynthetic bacteria.	Respiration occurs in all living organisms.

Complete the following food chains by writing the names of appropriate organisms in the blanks:

(i) Grass → ............... → Snake → ...............

(ii) ............... → Mouse ............... → Peacock

(i) Grass → Grasshopper → Snake → Hawk

(ii) Corn → Mouse → Snake → Peacock

Name these :

(a) Two aquatic plants which can be used for the experiment of photosynthesis.

(b) Two plants having variegated leaves.

(d) Four essentials for photosynthesis.

(e) Two main phases of photosynthesis.

(a) Hydrilla, Elodea

(b) Geranium, Croton

(d) Light, Chlorophyll, Carbon dioxide and water

(e) Photo-chemical phase, Biosynthetic phase

Match the terms given in column A with column B:

Column A	Column B
Chlorophyll	Removes/absorbs CO
Methylated spirit	Tests presence of starch
Potassium hydroxide	Traps solar energy
Iodine solution	Produces oxygen
Water	Bleaches chlorophyll

Column A	Column B
Chlorophyll	Traps solar energy
Methylated spirit	Bleaches chlorophyll
Potassium hydroxide	Removes/absorbs CO
Iodine solution	Tests presence of starch
Water	Produces oxygen

Complete the following by filling the blanks 1 to 5 with appropriate words/ terms/ phrases:

To test the leaf for starch, the leaf is boiled in water to (1) ............... . It is next boiled in methylated spirit to (2) ............... . The leaf is placed in warm water to soften it. It is then placed in a dish and (3) ............... solution is added. The region, which contains starch, turns (4) ............... and the region, which does not contain starch, turns (5) ............... .

To test the leaf for starch, the leaf is boiled in water to (1) kill the cells. It is next boiled in methylated spirit to (2) remove chlorophyll. The leaf is placed in warm water to soften it. It is then placed in a dish and (3) iodine solution is added. The region, which contains starch, turns (4) blue-black and the region, which does not contain starch, turns (5) brown. .

Write the exact location of each :

(a) Chlorophyll

(b) Chloroplast in the parts of a plant

(d) Guard cells

(e) Palisade cells

(a) Wall of thylakoid.

(b) Mesophyll cells of upper and lower epidermis of leaves.

(d) Stomata.

(e) Beneath epidermis.

Descriptive Type

Define the following terms:

(a) Photosynthesis

(b) Thylakoids

(d) Photolysis of water

(e) Polymerisation

(a) Photosynthesis — Photosynthesis is the process by which living plant cells, containing chlorophyll, produce food substances (glucose and starch), from carbon dioxide and water, by using light energy and release oxygen as a by-product.

(b) Thylakoids — Closely packed flattened sacs arranged in piles in the interior of chloroplasts are called Thylakoids.

(c) Chloroplast — Chloroplasts are minute oval bodies bounded by a double membrane which contains Thylakoids arranged in piles called Grana lying in a colourless ground substance called Stroma.

(d) Photolysis of water — Photolysis of water is defined as the splitting of H 2 O molecules into hydrogen ions and oxygen in the presence of light.

(e) Polymerisation — Polymerisation is the process in which several glucose molecules are transformed to produce one molecule of starch.

Given below is the figure of an experimental set-up, showing a physiological act of the plants. Study and answer the following questions.

(a) What is the objective of this experiment ?

(b) Name and define the process shown here.

(d) How do we destarch the leaves ?

(e) What will be the observation when we pour iodine solution over the bleached experimental leaf.

(f) Write a well-balanced equation of the above process.

(a) The objective of given experiment is to show that sunlight is necessary for photosynthesis.

(b) The process shown here is photosynthesis.

Photosynthesis is the process by which living plant cells, containing chlorophyll, produce food substances (glucose and starch), from carbon dioxide and water, by using light energy and release oxygen as a by-product.

(c) We destarch the leaves before experiment in order to remove the starch from leaves so that occurence of photosynthesis can be detected.

(d) To destarch the leaves the plant is kept in dark for 24-48 hours. This stops photosynthesis in the plant. During this time the starch already present in the leaves is translocated to storage organ of the plant fom the leaves.

(e) When we pour iodine solution over the bleached experimental leaf the area where starch is present turns blue.

(f) The equation for photosynthesis is given below:

Give reasons/explain:

(a) It is necessary to place a plant in the dark before starting an experiment on photosynthesis.

(b) It is not possible to demonstrate respiration in a green plant kept in sunlight.

(d) During the starch test, the leaf is -

boiled in water.
boiled in methylated spirit.

(a) A plant used for experiments on photosynthesis should initially be placed in the dark for 24 to 48 hours to destarch the leaves. During this period, all the starch will be removed from the leaves and stored in the storage organs. The leaves will not show the presence of starch. So the various experiments on photosynthesis can be carried out effectively.

(b) If a green plant is kept in bright light, it tends to use up all the CO 2 produced during respiration, for photosynthesis. Thus, the release of CO 2 cannot be demonstrated. Hence, it is difficult to demonstrate respiration as these two processes occur simultaneously.

(c) Due to more amount of chlorophyll on the upper surface more light is trapped. The chloroplasts are concentrated in the upper layers of the leaf which helps cells to trap the sunlight quickly. The upper surface is more green and shiny because it has a waxy coating to prevent loss of water due to evaporation.

(d) During the starch test,

The leaf is boiled in water to kill the cells.
The leaf is boiled in methylated spirit till it becomes pale-white due to the removal of chlorophyll. The leaf now becomes hard and brittle.

Distinguish between the following pairs on the basis of words indicated in the brackets ( )

(a) Light reaction and Dark reaction (end products)

(b) Producers and Consumers (organisms)

(d) Stoma and Stroma (structure)

(a) Differences between light reaction and dark reaction (end products) —

Light Reaction	Dark Reaction
ATP and NADPH are the end products of this reaction.	Glucose is the main product formed during dark reaction.
The water molecule split into hydrogen and oxygen.	No splitting of water.

(b) Differences between producers and consumers (organisms) —

Producers	Consumers
They are autotrophs.	They are heterotrophs.
They can convert inorganic substances into organic substances.	They cannot convert inorganic substances into organic substances.
It includes green plants and photosynthetic micro-organisms.	It includes herbivores and carnivores.
For example — green plants	For example — Animals

Grass	Grasshopper
Green grass being a producer is capable of producing its own food by photosynthesis.	Grasshopper is a primary consumer (herbivore) and directly feeds on producers like grass.

(d) Differences between stoma and stroma (structure) —

Stoma	Stroma
A stoma is a microscopic pore surrounded by two specialized guard cells found in the leaves and stems. Its main function is gaseous exchange.	Stroma is the colourless ground substance found in the chloroplast. It is the site of the light independent reactions of photosynthesis.

How would you demonstrate that green plants release oxygen when exposed to light?

Place some water plants (Elodea or Hydrilla) in a beaker containing pond water and cover them by a short-stemmed funnel.
Invert a test-tube full of water over the stem of the funnel. (Ensure that the level of water in the beaker is above the level of stem of the inverted funnel).
Place the apparatus in the sun for a few hours. Bubbles of the gas will collect in the test-tube.
Test the gas in the test-tube. A glowing splinter bursts into flame which shows the presence of oxygen.

Describe the main chemical changes which occur during photosynthesis in

Light reaction

Dark reaction

The light reaction occurs in two main steps:

Step 1 — Activation of chlorophyll The chlorophyll on exposure to light energy becomes activated by absorbing photons.

Step 2 — Splitting of Water The absorbed energy is used in splitting the water molecule (H 2 O) into its two components (Hydrogen and Oxygen) and releasing electrons.

2 H 2 O ⟶ energy of 4 photons 4 H + + 4 e − + O 2 2 H_2O \overset{\text{energy of 4 photons}}{\longrightarrow} 4H^+ + 4e^- + O_2 2 H 2 O ⟶ energy of 4 photons 4 H + + 4 e − + O 2

This reaction is known as photolysis of water.

End result of the products of photolysis The hydrogen ions (H + ) are picked up by a compound NADP (Nicotinamide adenine dinucleotide phosphate) to form NADPH.

N A D P + + e − + H + ⟶ enzyme N A D P H NADP^+ + e^- + H ^+ \overset{\text{enzyme}}{\longrightarrow} NADPH N A D P + + e − + H + ⟶ enzyme N A D P H

The oxygen (O) component is given out as molecular oxygen (O 2 ).

2 O ⟶ O 2 2O \longrightarrow O_2 2 O ⟶ O 2

The electrons (e - ) are used in converting ADP (adenosine diphosphate) into energy rich compound ATP (adenosine triphosphate) by adding one phosphate group P i (inorganic phosphate).

A D P + P i (inorganic phosphate) ⟶ A T P ADP + P_i \text{ (inorganic phosphate)} \longrightarrow ATP A D P + P i (inorganic phosphate) ⟶ A TP

This process is called photophosphorylation.

The reactions in this phase do not require light energy and occur simultaneously with the light reaction. The time gap between the light and dark reaction is less than one thousandth of a second. In the dark reaction, ATP and NADPH molecules (produced during light reaction) are used to produce glucose (C 6 H 12 O 6 ) from carbon dioxide. Fixation and reduction of carbon dioxide occurs in the stroma of the chloroplast through a series of reactions. The glucose produced is either immediately used up by the cells or stored in the form of starch.

Below is the summary of events in Light reaction and Light independent reactions of photosynthesis:

Structured / Application / Skill Type

Given below is a schematic diagram to illustrate some aspects of photosynthesis.

(a) Fill up the gaps, in blank spaces (1-4), by writing the names of the correct items.

(b) What phenomenon do the thick arrows A and B indicate?

(a) Blank spaces (1-4) are labelled below:

1 → Sunlight
3 → Glucose

(b) Phenomena represented by thick arrows A and B are:

A → Transpiration
B → Translocation

Given below is the representation of a certain phenomenon in nature with four organisms 1-4.

(a) Name the phenomenon represented.

(b) Name any one organism that could be shown at No .5

(d) Name one natural element which all the organisms 2-4 and even 5 are getting from No. 1 for their survival.

(a) Food chain

(b) Hawk, Eagle

A potted plant with variegated leaves was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours and then placed in bright sunlight for a few hours. Observe the diagram and answer the questions:

(a) What aspect of photosynthesis is being tested in the above diagram?

(b) Why was the plant placed in the dark before beginning the experiment?

(d) What will be the result of starch test when performed on leaf A shown in the diagram?

(e) Draw a neat and labelled diagram of a chloroplast.

(a) The above experiment is conducted to show that chlorophyll is necessary for photosynthesis.

(b) The plant was placed in the dark before beginning the experiment to destarch the leaves.

(d) After the starch test on leaf A, only the green parts of the leaf turn bluish, showing the presence of starch.

(e) Below diagram shows Chloroplast with its different parts labelled:

Given below is the diagram of an experimental set-up:

a. What is the objective of this experiment?

b. Will it work satisfactorily? Given reason.

c. What alteration (s) will you make in it for obtaining expected result?

d. Would you take any step before starting the experiment? Describe this step and explain its necessity.

(a) The objective is to prove that carbon dioxide is necessary for photosynthesis.

(b) No, the experiment will not work satisfactorily because, the beaker contains lime water which does not absorb CO 2

(d) Before starting the experiment, it is necessary to destarch the leaves of the plant by keeping the plant in complete darkness for 48 hours. This is because if the plant is not destarched, then the experiment will give false results because starch stored previously may be detected in the leaf placed in the beaker even if no starch is produced during the experiment.

Draw a neat diagram of the stomatal apparatus found in the epidermis of leaves and label the Stoma, Guard cells, Chloroplast, Epidermal cells, Cell wall and Nucleus.

Below diagram shows the stomatal apparatus found in the epidermis of leaves with all the different parts labelled:

Given below is the diagram of an experimental set-up (final stage). Study the same and answer the following questions :

(a) What is the main aim of the experiment?

(b) Oxygen gas shown in the experiment is released from which of the raw materials ?

(d) Name the chemical substance which can be added in water to enhance the process/rate of release of oxygen gas.

(e) Draw a neat and labelled diagram of the same experiment for its initial stage.

(a) The main aim of the experiment is to show that oxygen is produced during photosynthesis.

(b) Oxygen is released from Water (H 2 O).

(d) Sodium Bicarbonate

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How does carbon dioxide react with lime water?

Last updated at April 16, 2024 by Teachoo

When carbon dioxide reacts with lime water, a white precipitate of calcium carbonate is formed which turns lime water milky .

The reaction is as follows

CO 2 + Ca (OH) 2 -----> CaCO 3 + H 2 O

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Lime Water Test
In this session, I will doing some experiment from the chapter "Acid, Bases & Salt" of class 10.Here is the experiments playlist:You can also follow me at :i...
Lime water test ( Chemical reaction experiment class 10 CBSE )
Lime water test, Test for CO2
Limewater Carbon Dioxide Experiment for Kids
Procedure. **Day before preparations. Add 1 teaspoon of calcium hydroxide (slaked lime) to the large jar or bottle. Fill the bottle with distilled water and stir or shake (if your jar has a lid) vigorously for 1-2 minutes. Let stand undisturbed for 24 hours. **Day of procedures. After 24 hours, using the filter and filter paper, strain the lime ...
6. Life Processes
Experiment to prove release of CO 2 during respiration in Yeast. Add some yeast to fruit juice or sugar solution. Take this mixture in a test tube fitted with a one-holed cork. Fit the cork with a bent glass tube. Dip its free end into a test tube containing freshly prepared lime water. Air taken out through the tube makes lime water milky.
The Limewater Carbon Dioxide Test
Fill the small, shallow dish with limewater. Take modeling clay and mold it into a ring just below the bendable part of your straw. Add ¼ cup of water and ¼ cup of white vinegar into the water bottle. Take 1 square of toilet paper and spread some baking soda in the middle of the paper. Roll it up and twist the ends of the toilet paper so the ...
How does carbon dioxide react with limewater? Chemistry Q&A
Q. what happens when carbon dioxide reacts with lime water. Q. When carbon dioxide combines with lime water it turns lime water. Q. Carbon dioxide turns lime water _____. Q. Carbon dioxide turns lime water milky. Q. Balance This Equation. lime water with carbon dioxide gives calcium carbonate and water. also explain how it is done.
How to Make Limewater
2. Fill the jar with distilled or tap water. 3. Shake the jar vigorously for 1-2 minutes, then let it stand for 24 hours. 4. Being careful not to stir up the sediment, pour the clearer solution off the top of the jar through a clean coffee filter or filter paper. 5. Repeat the filtering step, if necessary, to obtain a clear limewater solution.
Lime water and carbon dioxide Experiment
Reewaz is blowing the lime water for the carbon dioxide test
Different Types of Reactions Experiment
In this article, we have discussed step by step procedure to perform CBSE Class 10 Science Practicals experiment Types of Reactions. It will help you understand the different types of reactions viz combination, displacement, decomposition, double displacement reaction on the following actions - water on quicklime, iron nails in CuSO 4, heat ...
Chapter 6: Photosynthesis
Get accurate answers of ICSE Class 10 Concise Biology Selina Chapter 6: Photosynthesis. ... No, the experiment will not work satisfactorily because, ... To obtain expected result replace the lime water from potassium hydroxide because it absorbs carbon dioxide. (d) Before starting the experiment, it is necessary to destarch the leaves of the ...
[Class 10] How does carbon dioxide react with lime water?
How does carbon dioxide react with lime water? Answer: When carbon dioxide reacts with lime water, a white precipitate of calcium carbonate is formed which turns lime water milky . The reaction is as follows. CO 2 + Ca (OH) 2 -----> CaCO 3 + H 2 O. Next: What are the different ways in which glucose is oxidized to provide energy in various ...
Lime water and CO2 Experiment || Class10th Biology
#respiration #limewaterexperiment#kunshisentertainmentIn this video you can learn the quantity of co2 is more in exhaled air than atmospheric air through an ...
PDF Page 1 ADAPTERS off tube positioned at
water pressure conditions. The pumps feature a ball-type, positive-action valve in the suction tube which prevents wa-ter backflow if the pressure is reduced. ASPIRATOR, FILTER PUMP, NALGENE Maximum free air pumping capacity of 11.5L per minute at a water flow rate of 6.5L per minute. Provides vacuum to 723.9mm Hg (28.5in. Hg). Operates ...
Sustainable use of laterite replaced with bottom ash as road
The proportion of bottom ash used varied from 10 to 50% by dry weight of the laterite, while the cement contents were 1, 3, 5, and 7% by dry weight of the laterite-bottom ash mixture. The experiments included unconfined compressive strength, splitting tensile strength, California bearing ratio, and durability against wetting-drying cycles.
CO2 turns lime water milky
Welcome to BestbuddyImportant keywords - CO2 turns lime water milky, exhaled air contain carbon dioxide, class 10 life process, class 10 life process Activit...