Wednesday, 27 April 2016

UPSC IAS Prelims Exam : Geography MCQs Set- 19( The Oceans)

1. Consider the following statements:
1. Salinity of the oceans decreases to pole wards.
2. The highest salinity is recorded near the Equator.
3. The highest salinity is observed between 20 to 40 degrees North latitude.
4. The zone between 40 to 60 Degree latitudes in the both hemispheres record low salinity.

Which of the above given statements are correct?

a. Only 1
b. Only 2
c. 1, 3 and 4
d. 1, 2 and 4

Ans: (c) 

Explanation:
 Generally, salinity decreases from Equator towards the pole but the highest salinity is seldom recorded near the Equator because high rainfall reduces the related proportion of salt. The highest salinity is observed between 20 to 40 degrees North latitude. The average salinity of oceans is 35 Percent.

2. Consider the following statements:
1. In the Atlantic Ocean the highest salinity is observed between 15 degree to 20 degree latitudes
2. Salinity is higher along the western margins than the eastern margin between 10-30 degree latitude in the South Atlantic
3. The average salinity of the Atlantic Ocean is 35.6 Percent.
4. Lake Van of Turkey has the highest salinity in all over the globe.

Which of the above given statements are correct?

a. 1 and 2
b. 3 and 4
c. 1, 3 and 4
d. All of the above

Ans: (d) 

Explanation:
 In Atlantic Ocean high salinity is not recorded at the Equator rather it is observed between 50-20 Degree latitudes. The average salinity of the Atlantic Ocean is 35.6 Percent. In South Atlantic Ocean between 10-30 degrees salinity is higher along the western margin than eastern margin. Lake Van of Turkey has the highest salinity in all over the globe.

3. Consider the following statements:
1. All the material which is accumulated at the floor of the ocean is ocean deposits.
2. The sediments derived from weathering and erosion of continental rocks are transported to the oceans by rivers, winds etc.
3. Volcanic eruption also provides sediments to the ocean deposits.
4. The decay and decomposition of marine organisms also contribute to the ocean deposits.

Which of the above given statements are correct?

a. Only 1
b. Only 2
c. 1 and 2
d. All of the above

Ans: (d) 

Explanation:
 The unconsolidated sediments derived from various sources deposited at the Sea floor are included in ocean deposits. The sediments derived from weathering and erosion of continental rocks are transported to the oceans by rivers, winds etc.

4. Consider the following statements:
1. In the regard of ocean deposits, the source of organic material is sea itself.
2. Organic material are grouped into two categories -  nerretic matter and pelagic matter.
3. Nerretic matter consists of remains of different types of algae.
4. Pelagic matter includes skeleton of marine organisms and plant remains.

Which of the above given statements are correct?

a. Only1
b. Only 2
c. 1 and 2
d. All of the above.

Ans: (c) 

Explanation:
 For Ocean deposits the source of organic material is sea itself. They include skeleton of marine organisms and plant remains. These materials are grouped into two types Nerretic matter and pelagic matter. Nerretic matter includes skeleton of marine organisms and plant remains whereas pelagic matter consists of remains of different types of algae.

5. Consider the following statements:
1. Tides are the most important of the all the oceanic movements.
2. The rise of sea water and its movements towards the coast is called the tide.
3. The sea waves generated by the Tides are called the Tidal waves.
4. There is much similarity in the height of high and low tides at different places in different oceans.

Which of the above given statements are correct?

a. Only 1
b. Only 2
c. 1,2 and 3
d. All of the above

Ans: (c) 

Explanation:
 Waves, currents and tides have vital significance among the various types of oceanic movements but tides are the most important of all the oceanic movements because the tidal currents affect the whole tidal mass from the sea surface to the bottom. The rise and fall of sea water due to gravitational forces of the Sun and the Moon are called tides.

6. Consider the following statements:
1. The moon creates high tides than the Sun on the Earth’s water surface.
2. The cause of this is that the Moon is only 3,84,000 Km from the Earth.
3. Two Tides and Ebbs are experienced twice at every place on the Earth’s water surface within 12 hours.
4. Each day tide is experienced at the same time.

Which of the above given statements are correct?

a. Only 1
b. Only 2
c. 1 and 2
d. All of the above.

Ans: (c) 

Explanation:
 The moon creates high tides than the Sun on the Earth’s water surface because of having greater gravitational force as the moon is only 3,84,000 Km from the Earth. Two Tides and Ebbs are experienced twice at every place on the Earth’s water surface within 24 hours. Each day tide is delayed by 26 minutes because the Moon also rotates on its axis while revolving around the Earth.

7. Match the following:
Table – I                                                                       Table – II

A. The position of the Sun, the Moon and the
Earth in a straight line.                                                     1. Conjunction
B.The position of the Sun and the Moon on one side
Of the Earth.                                                                   2. Syzygy
C.The position of the Earth between the Sun and the
Moon.                                                                            3. Perigee
D.The period of the nearest distance between the Moon
and the Earth.                                                                 4. Opposition

Codes:

a. A-2, B-1, C-4,D-3
b. A-1,B-2,C-3,D-4
c. A-2,B-1,C-3,D-4
d. A-1,B-2,C-4,D-3

Ans: (a) 

Explanation:
 The related position of the Sun, the Earth and the Moon are changeable. Position of the Sun, the Moon and the Earth in a straight line is called syzygy. The position of the Sun and the Moon on one side Of the Earth is conjunction. The position of the Earth between the Sun and the Moon is called opposition. Perigee is the period of the nearest distance between the Moon and the Earth.

8. Consider the following statements:
1. Most magmas are a combination of liquid, solid and gas.
2. Water vapour and carbon dioxide are the principal gases dissolved in a magma.
3. Basaltic magma is hotter than the silicic magma.
4. The magma solidified between sedimentary rocks in a horizontal position is known as dyke.

Which of these statements are correct?

a. 1, 2 and 3
b. 2, 3 and 4
c. 1 and 4
d. 1, 2 and 4

Ans: (a) 

Explanation:
 1, 2 and 3 statements are correct but not 4, because the magma solidified between sedimentary rocks in a horizontal position is known as “Sill”, but not Dyke (Dyke – solidification in vertical position).

9. Consider the following statements regarding the Earthquakes:
1. The intensity of earthquake is measured on Mercalli scale.
2. The magnitude of an earthquake is a measure of energy released.
3. Earthquake magnitudes are based on direct measurements of the amplitude of seismic waves.
4. In the Richter Scale, each whole number demonstrates a hundredfold increase in the amount of energy released.

Which of these statements are correct?

a. 1, 2 and 3
b. 2, 3 and 4
c. 1 and 4
d. 1 and 3

Ans: (a) 

Explanation:
 1, 2, 3 statements are correct but not 4, because in the Richter scale each whole number demonstrates a tenfold increase in the amount of energy.

10. Cloudy nights are warmer compared to clear cloudless nights, because clouds:
a. Prevent cold waves from the sky from descending on earth.
b. Reflect back the heat given off by earth.
c. Produce heat and radiate it towards earth
d. Absorb heat from the atmosphere and send it towards earth.

Ans: (b) 

Explanation:
 Cloudy nights are warmer compared to clear cloudless nights because clouds reflects back the heat given off by the earth.

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