UPSC Prelims 2020 Analysis

Explanation

Statement 1 is incorrect. OMT is measured up to the depth of the 26°C isotherm, but the 129-meter depth mentioned in the southwestern Indian Ocean during January-March is incorrect. The depth of the 26°C isotherm can vary depending on the region and season.

Statement 2 is correct. OMT collected during January-March helps in predicting the amount of rainfall during the monsoon. It is used to assess whether rainfall will be more or less than the long-term average, as variations in OMT influence monsoon behaviour.

Hence, option B is the correct answer.

Explanation

Option A is incorrect. Aksai Chin is located to the east of Ladakh, whereas the Siachen Glacier is situated to the northwest of it.

Option B is incorrect. Leh is located to the south of the Siachen Glacier. The glacier lies in the eastern Karakoram range, far north of Leh.

Option C is incorrect. Gilgit is in the Gilgit-Baltistan region, which is west of the Siachen Glacier. The glacier is not located to the north of Gilgit.

Option D is correct. The Siachen Glacier is located north of the Nubra Valley in the eastern Karakoram range of the Himalayas. It is the world's highest battlefield, where India maintains a military presence.

Hence, option D is the correct answer

Explanation

Pair 1 is incorrect. The Mekong River originates in the Tibetan Plateau and flows through China, Myanmar, Laos, Thailand, Cambodia, and Vietnam before emptying into the South China Sea, not the Andaman Sea.

Pair 2 is incorrect. The Thames River flows entirely within England and empties into the North Sea, not the Irish Sea.

Pair 3 is correct. The Volga River is the longest river in Europe. It originates in Russia and flows into the Caspian Sea.

Pair 4 is correct. The Zambezi River originates in Zambia and flows through Angola, Namibia, Botswana, Zimbabwe, and Mozambique before emptying into the Indian Ocean.

So, the correct pairs are 3 and 4. Hence, option C is the correct answer.

Explanation

The description provided matches the requirements for cotton cultivation.

• Subtropical nature and frost sensitivity: Cotton is a subtropical crop and is sensitive to frost. A hard frost can damage the cotton plants, making them unsuitable for cold regions.
• Frost-free days: Cotton requires at least 210 frost-free days, which is typical for its growth cycle. It thrives in regions with a long growing season, free from frost.
• Rainfall requirement: Cotton needs 50 to 100 cm of rainfall. The crop is drought-tolerant, but it still requires moderate rainfall for optimal growth.
• Soil type: Cotton grows best in light, well-drained soil that can retain moisture, providing the right balance for its deep root system.

Cotton is the right answer. Hence, option A is the correct answer.

Explanation

Statement 1 is incorrect. Jet streams occur in both the Northern and Southern Hemispheres. They are fast-moving air currents found at high altitudes, typically around 10-15 kilometers above the Earth's surface, and exist in both hemispheres.

Statement 2 is correct. Not all cyclones develop an eye. Only certain strong cyclones, especially intense hurricanes or typhoons, develop a well-defined eye—a calm, low-pressure area at the center of the cyclone surrounded by the strongest winds.

Statement 3 is incorrect. The temperature in the eye can be several degrees Celsius warmer (typically 2–10°C) than the outer regions of the storm. This warmth is due to subsiding (sinking) air in the eye, which compresses and heats up adiabatically. Hence , option C is the correct answer.

Explanation

Statement 1 is correct. The bud chip method involves raising sugarcane settlings in a nursery before transplanting them into the main field. This method reduces seed material requirements by using only the bud instead of the entire sett, leading to cost savings and better efficiency.

Statement 2 is incorrect. Multi-budded setts generally have a higher germination percentage than single-budded setts. Single-budded setts may face more difficulty in germination compared to setts with multiple buds, which provide better shoot emergence.

Statement 3 is incorrect. Under adverse weather conditions, large setts have better survival rates because they store more nutrients and moisture. Single-budded setts are more vulnerable to unfavorable conditions and may have lower survival rates.

Statement 4 is correct. Tissue culture techniques are successfully used for sugarcane cultivation. Settlings prepared from tissue culture help in producing disease-free, high-yielding plants and allow rapid multiplication of quality planting material.

Hence, option C is the correct answer.

Explanation

Major minerals are those specified in the first schedule appended in the MMDR Act. There is no official definition for major minerals in the MMDR Act.

Bentonite is a minor mineral. It is used in drilling mud, foundry sand, and civil engineering applications.

Chromite is a major mineral. It is the only ore of chromium, essential for stainless steel and alloy manufacturing.

Kyanite is a major mineral. It is a refractory mineral used in ceramics and high-temperature industries.

Sillimanite is a major mineral. It is also a refractory mineral with applications in metallurgy and industrial furnaces.

Therefore, Chromite, Kyanite and Sillimanite are major minerals, whereas Bentonite is a minor mineral.

Therefore, the correct answer is D.

Explanation

Statement 1 is correct. Like most of the pulses in India, Black gram pulse too can be cultivated both in kharif as well as in rabi season in India.

Statement 2 is incorrect. Chickpea pulse, also known as Chana, are the major pulse produced in India. It contributes more than 48% of the total pulse production in India. Since statement 1 is correct and 2 is incorrect, statement 3 is also incorrect through elimination.

Statement 3 is incorrect. The overall trend of area, production and yield of the last three plan periods have shown an increasing trend in production and productivity of Kharif Pulses.

The overall trend of area, production and yield of the last three plan periods have shown an increasing trend in the area however, production and productivity of Rabi Pulses declined during the XIth plan period from the Xth plan period and significantly increased during the XIIth plan period. Hence, option A is the correct answer.