(i) Caspian Sea (a) Largest lake
(ii) Tide (b) Periodic rise and fall of water
(iii) Tsunami (c) Strong seismic waves
(iv) Ocean currents (d) Streams of water moving along
definite paths
(i) (a) Water cycle ✓
(ii) (b) Equator ✓
(iii) (a) Tide ✓
(a) The rivers flowing into the oceans carry many dissolved minerals and salts along with it. When water evaporates, all the dissolved minerals and salt are left behind in the water making it salty. The salt present in ocean water is mainly sodium chloride.
(b) Almost three-fourth of our earth is covered with water, yet only 3% of this is fresh water, which can be used by us. The amount of fresh water remains constant but the population is rapidly increasing. To meet the requirements of this increasing population, we are overusing and polluting the existing sources of water. Factors like deforestation, industrial and agricultural pollution of rivers and lakes, wastage of water, pollution of ground water, etc., are responsible for the deteriorating quality of water today.
(a) The process of water falling back to the surface of the earth from the atmosphere in any form is known as precipitation.
(b) The process by which water continually changes its form and circulates between oceans, atmosphere, and land is known as water cycle.
(c) The factors affecting the height of the waves are:
(d) The factors affecting the movement of ocean water are:
(e) The rhythmic rise and fall of ocean water twice in a day are known as tides. They are caused by the strong gravitational pull of the sun and the moon.
(f) The streams of water flowing constantly on the surface of the ocean in definite directions are known as ocean currents.
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