Chapter 14: Water

    I. Multiple Choice Questions (MCQs).
    Q.1. Our planet earth is called
    a) water planet
    b) blue planet
    c) dwarf planet
    d) both (a) and (b)
    Answer: b) blue planet

    Q.2. About 97% of water as salty present in the
    a) sea
    b) river
    c) glaciers
    d) none of these
    Answer: a) sea

    Q.3. About 68% of the freshwater is available in the form of
    a) sea
    b) river
    c) ice caps and glaciers
    d) none of these
    Answer: c) ice caps and glaciers

    Q.4. Our body weight due to water is nearly
    a) 50%
    b) 60%
    c) 70%
    d) 80%

    Answer: (c) 70%
    Q.5. The earliest human settlements came up near sources of
    a) food
    b) water
    c) mountain
    d) forest
    Answer: (b) water
    II. Fill in the blanks by selecting appropriate words from the given list:
    List : Glacier, heating, water, free, combined, potable, cooling
    Q.1. No living organism can survive on the earth that does not have ________ in it.

    Q.2. Water is available in _____________ as well as in _____________ states.

    Q.3. _____________ is the major source of fresh water.

    Q.4. Water that is fit for human consumption is called _____________ water.

    Q.5. Water can be changed from one state to another by _____________ or _____________.

    Answer: 1- water,
    2- free, combined,
    3- Glacier,
    4- potable,
    5- heating, cooling

    III. Match the items of Column A with those of Column B.

    Answer: 1- c, 2-d, 3-b, 4-e, 5-a
    IV. Write ‘T’ for the true and ‘F’ for the false statements.
    1. Dead sea in Israel is so salty that people can float in it without sinking.
    2. The process by which plants release water through their leaves is called transpiration.
    3. Groundwater is not a renewable resource.
    4. The process of collecting and storing rainwater from roofs is rainwater harvesting.
    5. Evaporation is a process in which a gas or vapour turns to liquid at lower temperature.

    Ans 1-T, 2-T, 3-F, 4-T, 5-F

    V. Very Short Answer Questions.

    Q.1. What percentage of total amount of water is available as groundwater?
    Answer: 0.003 %

    Q.2. Write two vegetables and percentage of water in them. Answer:

    Q.3. Write two fruits and percentage of water in them. Answer:

    Q.4. Define potable water.
    Answer: Water fit for human consumption is called potable water.

    Q.5. Define transpiration.
    Answer: Transpiration is a process through which plants release water vapour through stomata from their leaves.

    VI. Short Answer Questions.

    Q.1. Write percentages of water available in different sources.
    Answer: About three-fourth of earth’s surface is covered with water. About 97% of water is present in the sea and oceans as salty water while remaining 3% is found as freshwater. Out of 3% of freshwater, about 2.997% of the freshwater is available in the form of ice cap or glaciers and only 0.003% is available as groundwater, river, pond, lakes, etc.

    Q.2. How can you say spring water is naturally filtered?
    Answer: Spring water is naturally filtered water as it passes through gravel and sand.

    Q.3. Discuss how water plays a vital role in various ways in our lives.
    Answer: Water plays vital role in various ways as follows :
    (a) It is essential for sustaining animal and plant life.
    (b) In agricultural activities (to grow our food crops).
    (c) For cleaning our bodies externally i.e., for taking a bath.
    (d) For cooking food.
    (e) For a large number of heavy industries.
    (f) For running hydroelectric and thermoelectric power plants.

    Q.4. Describe occurrence of water in different states. Explain with examples.

    Answer: Water is available both in free as well as in combined states. In a free state, it can be present in solid, liquid and gaseous states.
    (a) Solid state: Large amount of water is found in solid state, for example, ice or snow at vast regions of Arctic and Antarctic area.
    (b) Liquid state: Biggest reservoir of liquid water is ocean or sea. Rain is also a form of liquid water.
    (c) Gaseous State: It occurs mostly in vapour form–when water is heated, it evaporates, which on condensation, turns back to clouds, mist, fog, etc.

    In a combined state: It is present in carbohydrates, proteins, etc. Water is available in the crystalline form in salts.

    Q.5. Write different sources of water. Explain with examples.
    Answer: (a) Surface water : The water that we get on the surface is called surface water. Example- Rainwater, Spring and well water, River and lake water

    (b) Underground water : A part of rainwater gets absorbed by the ground. When water reaches nonporous layer, it cannot sink anywhere. This water is known as underground water. Example-Hand pump

    VII. Long Answer Questions.
    Q.1. What do you mean by water cycle? Discuss some salient features of the water cycle.
    Answer: Water constantly moves from the earth to the air and comes back on the earth again. The constant circulation of water from the earth to the atmosphere and back again to the earth is known as the Water Cycle.

    Salient Features of the Water Cycle
    (a) When a portion of earth’s surface becomes slightly hotter than the adjoining area, the air above this portion also becomes comparatively warmer. This gives rise to an air current.

    (b) Major part of the rainwater soaks into the ground and filters deep down to the impervious rock.

    (c) A part of the rainwater forms small water currents. Such currents join one another to give a large current called river.

    (d) Soon after the rain, the rivers are full to the brim.

    Q.2. Define flood and drought and their adverse effects on human life.

    Answer: Flood: Heavy rains lead to rise in the level of water in rivers, lakes and ponds. Thus, the water spreads over large areas causing floods.

    Effects of floods
    i. Diseases,
    ii. Starvation,
    iii. Loss of residential building and property,
    iv. Loss of human lives,
    v. Loss of domestic cattles,
    vi. Loss of standing crops,
    vii. Food chains are destroyed.

    Drought: The abnormally long period of insufficient or no rainfall is called drought. In this situation the soil continues to lose water due to evaporation and transpiration, and becomes dry. The groundwater is hardly found. In drought conditions, it is difficult to get food and fodder. Animals and humans die due to thirst and dehydration. When plants do not grow, cultivation suffers and farmers cannot grow food. This leads to extreme poverty since they have nothing to eat. No food, no money causes famine.

    Q.3. What do you mean by rainwater harvesting? Discuss some of the steps needed for conservation and management of water.
    Answer: The process of collecting and storing rainwater from roofs or a surface catchment is called rainwater harvesting.

    (a) Allow rainwater to go into the ground through roadside drains that collect rainwater.

    (b) Roof-rainwater harvesting: In this method rainwater during rains is collected from the rooftops to a storage tank through pipes. Instead of collecting rainwater in the tank, we can allow the pipes to go directly into the pit underground. This then seeps into the soil to recharge or refill the groundwater.

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