Class 3 Science - Air and Water - CBSE Worksheets Solutions

Multiple choice questions

Question 1: Which gas is used by the plants when they make food?
(a) Oxygen
(b) Carbon dioxide
(c) Nitrogen
(d) Water vapour

Correct Answer is Option B.

Plants are autotrophs, which means they produce their own food. They use the process of photosynthesis to transform water, sunlight, and carbon dioxide into oxygen, and simple sugars that the plant uses as fuel.

Question 2: How much of the Earth’s surface is covered with water?
(a) 25%
(b) 97%

(c) 71%
(d) 1%

Correct Answer is Option C.
Water covers about 71% of the earth's surface.

Question 3: Water is found in this form:
(a) Solid
(b) Liquid
(c) Gas
(d) All of these

Correct Answer is Option D.

Water can occur in three states: solid (ice), liquid, or gas (vapor).

Question 4: Which of these is true for burning?
(a) Oxygen is formed.
(b) Carbon dioxide is formed.
(c) Carbon dioxide is used up.
(d) Oxygen and carbon dioxide are neither formed nor used up.

Correct Answer is Option B.

During combustion or burning, carbon from fossil fuels combine with oxygen in the air to form carbon dioxide and water vapor.

Question 5: Which of the following helps to save water?
(a) Using a hose pipe to water plants.
(b) Closing the tap while brushing your teeth.
(c) Throw away the water used to wash vegetables and fruits.
(d) Using a shower to bathe.

Correct Answer is Option B.
Closing the tap while brushing your teeth will save water. 

Fill in the blanks

Question 6:

• Air is a mixture of gases.
• All living things need oxygen to breathe.
• Flowing water is used to generate electricity.
• When wind moves gently it is called breeze.
• Ice melting from glaciers feeds rivers and lakes.

EduRev Tips:

• The air around us is a mixture of gases, mainly nitrogen and oxygen
• Most living things need oxygen to survive. Oxygen helps organisms grow, reproduce, and turn food into energy.
• Hydroelectric energy is a form of renewable energy that uses the power of moving water to generate electricity.
• Breeze: Slow and gentle moving wind is called breeze.
• Ice melting from glaciers feeds rivers and lakes.

Match the following

Question 7:
(a) Windmill            (i) Drinking water
(b) Potable water    (ii) Solid state
(c) Oxygen             (iii) Storm
(d) Ice cube            (iv) Electricity
(e) Strong wind      (v) Breathing

(a) Windmill -  (iv) Electricity 

(b) Potable - (i) Drinking water 

(c) Oxygen - (v) Breathing

(d) Ice cube - (ii) Solid state

(e) Strong wind - (iii) Storm

True & False

Question 8:

• Earth is also called as green planet. True
• Potable water is the water which is safe to drink. True
• We should use hose pipes to clean our cars. False
• Air is required for burning. True
• Plants do not need water for making their food. False

EduRev Tips:

• Earth is called a green planet due to the presence of plants on it.
• “Potable water” simply means water that is safe to drink, and it is becoming scarcer in the world.
• It destroys lots of water.
• Oxygen: Air contains about 21 percent oxygen, and most fires require at least 16 percent oxygen content to burn. Oxygen supports the chemical processes that occur during fire. When fuel burns, it reacts with oxygen from the surrounding air, releasing heat and generating combustion products (gases, smoke, embers, etc.).
• Plants need water for making their food.

Answer the following questions in brief

Question 9: What is air? What does air contain?

Air is made up of nitrogen, oxygen, argon, carbon dioxide, neon, helium, krypton, hydrogen, and xenon. It does not include water vapor because the amount of vapor changes based on humidity and temperature.

Question 10: Write any three uses of air.

The air in our atmosphere acts as insulation, keeping the Earth from getting too cold or too hot. Ozone, another type of gas in the air, also protects us from too much sunlight. Air in the atmosphere can also protect us from meteoroids.

Question 11: What are the sources of water?

The main sources of water are surface water, groundwater and rainwater.

Question 12: What are the three states in which water can be found in? 5. Mention five ways to save water.

Water can occur in three states: solid (ice), liquid, or gas (vapor).

Ways to save water: 

• Be aware and spread awareness. 
• Take quick showers. 
• Fix any leaky taps at home. 
• Use one utensil for drinking water. 
• Don't pour excess drinking water in the sink.

Observe the following image and answer the questions given below.

Question 13: Identify the two gases A and B shown in the given image.

(a) _______________

(b) _______________

Question 14: Name the two processes shown in the given image.

_______________