Which of the following is not a renewable source of energy?

The correct answer is D, Maharashtra. Maharashtra has by far the largest number of large dams in India, more than two thousand of the roughly 5,300 listed in the National Register of Large Dams, which is close to half the country's total. The rivers of its Deccan plateau, its dependence on irrigation for sugarcane and its long record of building storage projects explain the number, and Koyna, Jayakwadi, Ujani and Bhatsa are among its best known dams. Madhya Pradesh and Gujarat come next on the list. A is wrong because Rajasthan is dry and has few perennial rivers to dam, so its count is much smaller. B is wrong because Tamil Nadu has thousands of tanks but far fewer large dams. C is wrong because Gujarat, though high on the list and home to the Sardar Sarovar, stands behind Maharashtra. Exam tip: most large dams - Maharashtra, then Madhya Pradesh and Gujarat; a large dam is one more than 15 metres high.

The correct answer is C, Loo - Hot wind. The Loo is the strong, dry and very hot wind that blows over the plains of north and north-west India during the day in May and June. It moves from the west towards the east across Rajasthan, Punjab, Haryana, Delhi, Uttar Pradesh and Bihar, often pushing afternoon temperatures above 45 degrees Celsius, and long exposure to it can cause heat stroke. It dies down once the monsoon arrives in late June. A is wrong because Kaal Baisakhi is not an autumn wind; it is the violent evening thunderstorm of April and May in West Bengal, Odisha and Assam that brings sudden rain and squalls. B is wrong because trade winds are the steady tropical winds blowing from the subtropical high pressure belts towards the equator, not winter snow storms. D is wrong because the Loo is a summer wind, not a winter stormy wind. Exam tip: Loo - hot summer wind of the northern plains; Kaal Baisakhi - pre-monsoon thunderstorm of eastern India; mango showers - pre-monsoon rain of Kerala and Karnataka.

The correct answer is C, Doab. Doab, from the Persian words for two and water, is the name for the tract of land between two rivers. The Punjab plains, built by the Indus and its tributaries, are divided into such tracts, among them the Bari doab between the Beas and the Ravi, the Bist doab between the Beas and the Satluj, the Rachna doab between the Ravi and the Chenab and the Chaj doab between the Chenab and the Jhelum. Option A is wrong because a Dun is a longitudinal valley between the Shiwaliks and the Lesser Himalaya. Option B is wrong because Bhabar is the pebble belt at the foot of the Shiwaliks. Option D is wrong because Karewas are the lake deposits of the Kashmir valley on which saffron is grown.

The correct answer is D, Aravalli Hills. The Purvanchal or Eastern Hills are the southward continuation of the Himalayas beyond the eastern bend of the Brahmaputra, and they are made up of the Patkai Bum, the Naga Hills, the Manipur Hills and the Mizo or Lushai Hills. They are lower than the main Himalayan ranges and are composed largely of soft sandstone. The Aravalli, by contrast, is one of the oldest fold mountain systems in the world, a residual range running north-east from Gujarat through Rajasthan to Delhi, with Guru Shikhar on Mount Abu as its highest point. Option A is wrong because the Patkai Bum lies along the Arunachal Pradesh border with Myanmar. Option B is wrong because the Naga Hills are in Nagaland, and Option C is wrong because the Mizo Hills are in Mizoram.

The correct answer is B, Brahmaputra. Majuli lies in the Brahmaputra in Assam and is counted the largest river island in the world. The Brahmaputra carries an enormous load of silt from a young, rapidly eroding basin, and because its channel is braided and shifts often, it has built large islands and sandbars called chars. Majuli is also a centre of Assamese Vaishnavite culture, with its satras or monasteries. Option A is wrong because the Ganga's delta holds Sagar Island and the Sundarbans, which are delta islands rather than the largest river island. Option C is wrong because the Godavari is a peninsular river with a delta on the east coast but no island of this size. Option D is wrong because most of the Indus basin lies outside India today.