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Q1. What do you understand by aquifer?

Solution

At some places the groundwater is stored between layers of hard rock below the water table. This is known as an aquifer.

Q2. The groundwater stored between the layers of hard rock below the water table is known as

• 1) Water table
• 2) Water peak
• 3) Aquifer
• 4) Infiltered water

Solution

The groundwater stored between the layers of hard rock below the water table is known as aquifer.

Q3. Wastewater generated in hospitals primarily consists of

• 1) Plastic
• 2) Dead debris
• 3) Radioactive substances
• 4) Acids and bases

Solution

Wastewater from hospitals contains several types of disease-causing germs and radioactive substances used in the treatment of diseases.

Q4. Leaking ___________ is a source of huge water wastage.

Solution

Taps

Q5. What is infiltration? How does it occur?

Solution

The process of seeping of water into the ground is called infiltration. The rainwater and water from other sources such as rivers and ponds seeps through the soil and fills the empty spaces and cracks deep below the ground.

Q6. List the solid, liquid and gaseous forms of water in our surrounding.

Solution

1. Solid form of water is snow and ice which is present at the poles of the Earth. 2. Liquid form of water is present in lakes, rivers, oceans etc. 3. Gaseous form of water is the water vapour present in the air around us.

Q7. The method of recharging groundwater by collecting rainwater is called

• 1) Sprinkler system
• 2) Rainwater harvesting
• 3) Drip irrigation
• 4) Rooftop harvesting

Solution

The method of recharging groundwater by collecting rainwater is called rainwater harvesting.

Q8. (a) What do you understand by rainwater harvesting?(b) Mention any two habits that can be done to save water at home.

Solution

(a) The activity of collecting rainwater directly or recharging it into ground to improve ground water storage in the aquifer is called rain water harvesting.(b)(i) Turning off taps while brushing.(ii) Mopping the floor instead of washing.(iii) Reducing flow of tap water while washing utensils.(Any two)

Q9. When is 'World Water Day' celebrated every year?

• 1) 24^th March
• 2) 25^th March
• 3) 23^rd March
• 4) 22^nd March

Solution

World Water Day is celebrated on 22^nd March every year.

Q10. The water found below the water table is called

• 1) Sub-soil water
• 2) Aquifer
• 3) Groundwater
• 4) Recharged water

Solution

The water found below the water table is called groundwater.

Q11. Which of the following is not an inorganic impurity present in contaminated water?

• 1) Phosphates
• 2) Metals
• 3) Nitrates
• 4) Dead and decaying organic matter

Solution

Inorganic impurities consist of traces of metals, nitrates and phosphates. Dead and decaying matter is an organic impurity present in contaminated water.

Q12. How much area of the Earth's surface is covered with water?

• 1) Two-third
• 2) Half
• 3) One-third
• 4) Three-fourth

Solution

Nearly, three-fourth area of the Earth's surface is covered with water. Water is found in ponds, rivers, lakes and oceans.

Q13. (a) Identify A, B and C in the above figure. (b) How do industries contribute to ground water depletion?

Solution

(a)A - Water tableB - AquiferC - Stream (b) The number of industries is increasing continuously to cater to the needs of the growing population. Water is needed at several steps in all the industrial production process and this water is usually drawn from the ground. Thus industries contribute to ground water depletion.

Q14. What is shown in the below figure?

Solution

The above figure shows drip irrigation in a field.

Q15. Give two disadvantages of drip irrigation.

Solution

Two disadvantages of drip irrigation are: 1. It leads to blockage of water if not filtered correctly. 2. The lifetime of tubes or pipes used in this type of irrigation may be shortened by the sun rays causing wastage of water.

Q16. The technique of watering plants by making use of narrow tubes with small holes which deliver water directly at the base of the plant is called

• 1) Sprinkler irrigation
• 2) Rooftop harvesting
• 3) Canal irrigation
• 4) Drip irrigation

Solution

The technique of watering plants by making use of narrow tubes with small holes which deliver water directly at the base of the plant is called drip irrigation.

Q17. What is drip irrigation? Why is this technique advantageous in regions of water scarcity?

Solution

Drip irrigation is a technique of watering plants by making use of narrow tubings which deliver water directly at the base of the plant. Water falls drop by drop just at the position of the roots. Hence water is not wasted at all. Thus, it proves advantageous in regions of water scarcity.

Q18. Write any three advantages of water harvesting.

Solution

(i) Rainwater harvesting can reduce flooding in city streets. (ii) Sea water intrusion in coastal areas can be arrested. (iii) The ground water can be recharged and conserved . (iv) Rainwater harvesting can reduce topsoil loss. (v) It can improve plant growth. (Any three)

Q19. The water that is fit for use is called fresh water.

• 1) False
• 2) True

Solution

True

Q20. (a) On digging a hole in the ground near a water body, we find the soil to be moist. Why?(b) How can we pump out the water in the aquifers?

Solution

(a) The moisture in the soil indicates the presence of underground water. (b) Water in the aquifers can usually be pumped out with the help of tube wells or hand pumps.

Q21. What happened to the bawris with time? Why are they being revived today?

Solution

Bawri was the traditional way of collecting water. With time the bawris fell into disuse and garbage started piling in these reservoirs. However due to acute water shortage, people in these areas began reviving these bawris and managing their water needs well, inspite of scanty rains.

Q22. Which two natural forces may deplete the water table?

Solution

Scanty rainfall and hot winds are natural forces that may deplete the water table.

Q23. List three reasons which are responsible for water shortage.

Solution

1. Rapid growth of industries 2. Increasing population 3. Mismanagement of water resources

Q24. __________________ in the soil indicates the presence of underground water.

Solution

Moisture

Q25. Why do Indian farmers have to use groundwater for irrigation?

Solution

A majority of farmers in India depend upon rains for irrigating their crops. Irrigation systems such as canals are there only in a few places. Even these systems may suffer from lack of water due to erratic rainfall. Therefore, farmers have to use groundwater for irrigation.

Q26. Discuss how increasing population causes depletion of water table?

Solution

Increasing population creates demand for construction of houses, shops, offices, roads and pavements. This decreases the open areas like parks, and playgrounds which affects the seepage of rainwater into the ground. Also, increasing population consumes more water for all their activities. So, the increasing population ends up consuming more groundwater as well as allowing lesser water to seep into the ground. This results in depletion of water table.

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