Daily Static Quiz Prelims Practice 2027
The Benguela Current flows north along the south-west coast of Africa, is cold and supports a rich upwelling ecosystem. The Kuroshio is a warm current in the North Pacific, the Brazil Current is a warm current in the South Atlantic, and the Gulf Stream is a warm current that warms north-western Europe.
- The average salinity of the world’s oceans is about 35 parts per thousand.
- Surface salinity is generally highest in the tropical belt around 20°–30° latitudes.
- The Baltic Sea has lower salinity than the Red Sea.
- Salinity is generally higher near river mouths because of the large inflow of dissolved salts.
Statement 1 is correct — average ocean salinity is around 35 ppt. Statement 2 is correct — the subtropics have high evaporation and low rainfall, while the equator itself is less saline because of heavy rainfall. Statement 3 is correct — the Baltic is low in salinity because of large river inflow and low evaporation, while the Red Sea is very saline because of intense evaporation and little river input. Statement 4 is incorrect — river inflow dilutes seawater and lowers salinity near river mouths.
- Assertion (A): Neap tides occur when the Sun and the Moon are at right angles to the Earth.
- Reason (R): At neap tide, the gravitational pulls of the Sun and the Moon act against each other, so high tides are lower than usual.
A is correct — neap tides occur around the first and last quarter of the Moon, when the Sun–Earth–Moon angle is about 90°. R is correct and explains A — because the Sun’s pull acts at right angles to the Moon’s, the two partly cancel and the tidal range is at its minimum. Spring tides, by contrast, occur at new moon and full moon, when the Sun, Earth and Moon are in a straight line (syzygy) and the pulls add up.
The Somali Current flows north-east during the south-west monsoon and south-west during the north-east monsoon, the only major current to change direction in this way. The West Australian Current is a cold current flowing northward along western Australia, while the Agulhas and Mozambique currents are warm currents flowing southward along the east coast of Africa.
- Statement 1: Coral bleaching occurs when corals expel their symbiotic algae (zooxanthellae) under stress such as rising sea temperature.
- Statement 2: In India, coral reefs are found along the Odisha and West Bengal coasts near the Ganga delta.
Statement 1 is correct — loss of zooxanthellae removes both the coral’s colour and much of its food supply, which can kill the coral if the stress persists. Statement 2 is incorrect — corals need clear, saline, warm water, which the turbid, freshwater-rich delta coasts of Odisha and West Bengal do not provide. India’s reefs occur in the Gulf of Kachchh, the Gulf of Mannar and Palk Bay, the Andaman and Nicobar Islands and Lakshadweep.
