Questions for Practice
1. About how much of all the water on Earth is salty seawater?
a) About one quarter
b) About half
c) About 97 per cent
d) All of it
View answer
Answer: c) About 97 per cent
Explanation: Nearly all of Earth's water is in the oceans and is salty. Only a small part is fresh water that we can use.
2. Where is most of Earth's fresh water found?
a) In rivers
b) In ponds and lakes
c) In clouds
d) Frozen in glaciers and ice sheets
View answer
Answer: d) Frozen in glaciers and ice sheets
Explanation: Most fresh water is locked up as ice. Much of the rest is under the ground. Rivers and lakes hold only a tiny part.
3. The layer of rock, sand or gravel under the ground that holds water is called
a) an aquifer
b) a glacier
c) a canal
d) a delta
View answer
Answer: a) an aquifer
Explanation: An aquifer stores groundwater in the gaps between grains of sand, gravel and rock. Wells and borewells draw water from it.
4. Villagers in Rajasthan build small mud walls across slopes to hold back rainwater so that it soaks into the ground. What are these called?
a) Baolis
b) Johads
c) Canals
d) Tankas
View answer
Answer: b) Johads
Explanation: A johad holds rainwater long enough for it to soak in and refill nearby wells. A baoli is a stepwell, and a tanka is an underground tank.
5. Which of these uses the most fresh water around the world?
a) Drinking
b) Cooking
c) Farming
d) Bathing
View answer
Answer: c) Farming
Explanation: Growing crops uses more fresh water than homes and factories put together. That is why methods such as drip irrigation save so much water.
6. Kabir spreads dry leaves and straw on the soil around his plants. How does this help save water?
a) It keeps the soil damp by slowing down evaporation
b) It makes the plants grow taller overnight
c) It turns the leaves into rainwater
d) It stops the plants from needing sunlight
View answer
Answer: a) It keeps the soil damp by slowing down evaporation
Explanation: This covering is called mulch. It shades the soil, so water does not dry up as fast and the plants need watering less often.
7. Which water from the house is best to reuse for watering plants?
a) Water flushed from the toilet
b) Water used to wash rice and vegetables
c) Water used to clean paint brushes
d) Water mixed with bleach after cleaning the floor
View answer
Answer: b) Water used to wash rice and vegetables
Explanation: This water is only a little dirty and has no harmful chemicals, so plants can use it. Toilet water, paint water and bleach water can harm plants and people.
8. "Catch the rain, where it falls, when it falls" is the message of which campaign?
a) Swachh Bharat Mission
b) Jal Shakti Abhiyan: Catch the Rain
c) Digital India
d) Fit India Movement
View answer
Answer: b) Jal Shakti Abhiyan: Catch the Rain
Explanation: This Government of India campaign asks people to build tanks, recharge pits and check dams before the monsoon, so that more rainwater is saved when the rains come.
9. What does a sewage treatment plant do?
a) It makes rain fall over a city
b) It turns seawater into ice
c) It removes most of the dirt and germs from used water so that it can be released or reused safely
d) It stores rainwater from rooftops
View answer
Answer: c) It removes most of the dirt and germs from used water so that it can be released or reused safely
Explanation: Used water from homes travels through sewers to the plant. After cleaning, it can go back into a river or be used for parks and building work.
10. Put the steps of a rooftop rainwater harvesting system in the correct order.
P: The water passes through a filter
Q: Rain falls on the roof
R: The water is stored in a tank
S: Pipes carry the water down
a) Q, S, P, R
b) S, Q, R, P
c) P, Q, S, R
d) Q, P, R, S
View answer
Answer: a) Q, S, P, R
Explanation: Rain falls on the roof, pipes bring it down, a filter removes leaves and dirt, and then the clean water is stored in the tank.
