The Hydrosphere

Total Questions: 15

1. With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct? [I.A.S. (Pre) 2020]

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Correct Answer: (b) 2 only

Solution:The 26°C isotherm is noticed at depths varying between 50-100 metres. During January-March, the mean 26°C isotherm in the South western Indian Ocean is at a depth of 59 metres. Ocean mean temperature (OMT) compared to sea surface temperature (SST) better predicts whether the total amount of rainfall that India will receive during monsoon season will be less or more than the long term mean of 887.5 mm.

2. The surface of the earth covered with water is approximately? [41st B.P.S.C. (Pre) 1996]

(a) One-fourth
(b) Half
(c) Two-thirds
(d) Three-fifth (3/5)

Correct Answer: (c) Two-thirds

Solution:Around 29% (29.1%) of the total surface Area of the Earth is land (about 148172000 sq. km) and 71% (70.9%) part (about 361900000 sq. km) is covered by ocean. Hence, the surface of earth covered with water is approximately more than two-thirds of the total surface area.

3. On the sea level, the nearest place to the center of earth is? [38th B.P.S.C. (Pre) 1992]

(a) North pole
(b) Tropic of Capricorn
(c) Tropic of Cancer
(d) Tropic of Equator

Correct Answer: (a) North pole

Solution:The nearest point to the centre of the Earth lie near Arctic Ocean (at the depth of 4 km from the surface) which is at the 6353 km far from the centre of the Earth.

4. Datum line : [U.P.P.C.S. (Pre) 1991. U.P.P.C.S. (Pre) 1994]

(a) Is a horizontal line to the sea level from where heights and depths are measured
(b) Is the mean of primary and secondary data
(c) International date line
(d) Is an imaginary line that passes through zero degree meridian

Correct Answer: (a) Is a horizontal line to the sea level from where heights and depths are measured

Solution:The Datum line is a horizontal line to the sea level from where all the elevations and depths are measured. A datum line, or datum, is a reference point or surface used to establish a standard for measuring elevations or depths. In surveying, mapping, navigation, and other fields, the datum line serves as a baseline for determining the height of land or the depth of the sea.

5. The part of our hydrosphere is – [Uttarakhand P.C.S. (Pre) 2010]

(a) Atlantic Ocean
(b) Indian Ocean
(c) Pacific Ocean
(d) Antarctica Ocean

Correct Answer: (c) Pacific Ocean

Solution:The area of given oceans is as follows – Pacific Ocean (155557000 sq. km), Atlantic Ocean (76762000 sq. km), Indian Ocean (68556000 sq. km), Southern Ocean (20327000 sq. km) and Arctic Ocean (14056000 sq. km). Hence largest part of our hydrosphere is the Pacific Ocean.

6. A ridge of 64000 km. length and 2000 km to 2400 km width passing through the north and south Atlantic oceanic basin enter into the south pacific oceanic basin through Indian oceanic and then from the middle of Australia and Antarctic. This ridge is – [47th B.P.S.C. (Pre) 2005]

(a) Socotra-Lakshadweep - Changos-Ridge
(b) Pacific - Antarctica Ridge
(c) Dolfin - Challenger Ridge
(d) Mid Oceanic Ridge

Correct Answer: (d) Mid Oceanic Ridge

Solution:Above qualities are related to Mid Oceanic Ridge. Mid Oceanic Ridge encircles the globe in the length of approximately 40390 miles or 65000 kilometer, covering Arctic, Atlantic, Indian and the Pacific Oceans. This is the single largest geological phenomena upon the surface of Earth.

7. Where is ‘Ninety East Ridge’ situated? [53rd to 55th B.P.S.C. (Pre) 2011]

(a) Pacific Ocean
(b) Indian Ocean
(c) Atlantic Ocean
(d) Arctic Ocean

Correct Answer: (b) Indian Ocean

Solution:Ninety East Ridge (90° E Ridge) is the name of a ridge located in the Indian Ocean. Located near 90° east longitude (meridian), this ridge is 5000 km long parallel to it and stretches across 40° south latitude to 10° northern latitude with an average width of 200 km.

8. The tension of gravitational water in the ground is – [U.P.U.D.A./L.D.A. (Spl) (Mains) 2010]

(a) below 1/3 atmosphere
(b) At 1.25 atmosphere
(c) At 5 atmosphere
(d) At 15 atmosphere

Correct Answer: (a) below 1/3 atmosphere

Solution:Gravitational water occupies the larger soil pores (macropores) and moves down readily under the force of gravity. Gravitational water under the surface of soil remains in a state of zero or less than 1/3 of the atmosphere.

9. Consider the following statements: [I.A.S. (Pre) 2010]

1. On the planet Earth, the fresh water available for use amounts to about less than 1% of the total water found.

2. Of the total freshwater found on the planet Earth, 95% is bound up in polar ice caps and glaciers.

Which of the statements given above is/are correct?

(a) 1 only
(b) 2 only
(c) Both 1 And 2
(d) Neither 1 nor 2

Correct Answer: (a) 1 only

Solution:96.5% of the total water available on Earth is salt water found in Ocean. Out of the remaining 2.5% Fresh water, 1.7% is in the form of glaciers and polar ice, which is unusable for humans. So in this way total available fresh water to use is less than 1% of the total water available on earth. Out of total amount of fresh water (2.5%), 68.7% is found in the form of glaciers and polar ice, 30.1% in the form of underground water, 0.3% in the form of surface water and remaining 0.9% is found in other forms. Hence only statement (1) is correct.

10. With reference to the water on the planet Earth, consider the following statements: [I.A.S. (Pre) 2021]

1. The amount of water in the rivers and lakes is more than the amount of groundwater.

2. The amount of water in polar ice caps and glaciers is more than the amount of groundwater