Q1. Which of the following statements is true?
(a) Both salinity and density of sea increase with depth
(b) Both salinity and density of sea decrease with depth
(c) Salinity increases but density of sea decreases with depth
(d) Salinity decreases but density of sea increases with depth
(UPSC Prelims 1981)
Answer: (a) Both salinity and density of sea increase with depth
Explanation: As depth increases, temperature drops, causing density to rise. Simultaneously, salinity tends to increase due to less mixing and evaporation effects, making deeper ocean layers denser and saltier than surface waters.
2. Match the columns:
| Column I | Column II |
|---|---|
| A. South-eastern coast of U.S.A. | 1. Florida current |
| B. West coast of South Africa | 2. Kuroshio current |
| C. South-western coast of South America | 3. Benguela current |
| D. South-eastern coast of Japan | 4. Peruvian current |
Select the correct answer using the codes given below:
| A | B | C | D | |
|---|---|---|---|---|
| (a) | 2 | 3 | 4 | 1 |
| (b) | 1 | 2 | 3 | 4 |
| (c) | 3 | 4 | 1 | 2 |
| (d) | 4 | 1 | 2 | 3 |
Answer: (a)
Explanation:
The Florida Current flows along the south-eastern coast of the U.S.A. (A–1).
The Benguela Current is found along the west coast of South Africa (B–3).
The Peruvian (Humboldt) Current flows along the south-western coast of South America (C–4).
The Kuroshio Current is located off the south-eastern coast of Japan (D–2).
Hence, the correct matching sequence is 2341.
Q3. Mean Sea Level (MSL) is the
(a) Average level of the sea
(b) Height of water above ground level
(c) Average height of waves
(d) None of the above
(UPSC Prelims 1986)
Answer: (a) Average level of the sea
Explanation: Mean Sea Level (MSL) is the average height of the sea’s surface, used as a reference point for measuring elevation and altitude. It is calculated over a long period to account for tidal variations.
Q4. Which of the following are known as coastlines of submergence ?
(a) Uplifted lowland
(b) Ria Coasts
(c) Emergent upland
(d) None of the above
(UPSC Prelims 1987)
Answer: (b) Ria Coasts
Explanation: Ria coasts are formed when river valleys are submerged due to rising sea levels, creating drowned coastlines. These are classic examples of coastlines of submergence, often seen in western Europe.