Which ministry of the Government of India is responsible for the promotion of renewable energy?

The correct answer is D, anthracite. Anthracite is the oldest and hardest grade of coal, with the highest proportion of carbon, so it gives the most heat for its weight and burns with a clean, almost smokeless flame. Option A is wrong because bituminous coal, though the grade most widely used in industry and in power stations, stands below anthracite in carbon content and produces more smoke. Option B is wrong because lignite, also called brown coal, is a low grade with high moisture, used mainly in power stations built at the mine itself. Option C is wrong because peat is the first stage of the process, little more than partly decayed plant matter, with the least carbon and the most moisture of the four. The rising order to remember is peat, lignite, bituminous, anthracite.

The correct answer is D, lower. A geothermal plant takes steam or hot water from a natural underground reservoir, whose temperature is set by the rock and rarely approaches what a furnace can produce, so both the temperature and the pressure at the turbine are well below those of a coal-fired steam plant, and the thermal efficiency is correspondingly lower. Options B and C are wrong for the same reason: no natural reservoir is hotter than a boiler fired deliberately, and quoting higher values confuses the depth of the source with its temperature. Option A is wrong because the two are not comparable either; the gap is large enough that geothermal turbines are designed differently, often working on a separate fluid that boils at a low temperature. What geothermal loses in efficiency it gains in fuel cost, which is nil, and in emissions.

The correct answer is B, Gurugram in Haryana. The alliance has its secretariat on the campus of the National Institute of Solar Energy at Gwal Pahari in Gurugram, and because it rests on a framework agreement among its members it is the first treaty-based international organisation to be headquartered in India. Option A is wrong because although the alliance is closely linked with the Indian government, the secretariat is not in New Delhi itself. Option C is wrong because Bengaluru hosts many renewable energy firms and research bodies but no organ of the alliance. Option D is wrong because Paris is where the alliance was launched, jointly by India and France at the climate conference of 2015, and candidates often confuse the place of launch with the seat of the secretariat.

The correct answer is C, 2010. The mission was launched in January 2010 as one of the eight national missions under the National Action Plan on Climate Change, and its aim was to make solar power competitive by building capacity in stages and by supporting domestic manufacturing. Option A is wrong because 2006 is the year the ministry took its present name, the Ministry of New and Renewable Energy, which is a separate landmark often placed among the options. Option B is wrong because 2008 is the year the National Action Plan on Climate Change itself was released, that is the umbrella under which the mission was later launched. Option D is wrong because 2015 is the year of the Paris climate conference and of the launch of the International Solar Alliance, five years after the national mission began.

The correct answer is B, natural gas. Natural gas is a fossil fuel formed over millions of years from buried organic matter; the stock is fixed, so every unit burnt is gone, and it releases carbon dioxide when burnt, although less than coal for the same heat. Option A is wrong as an answer because tidal energy comes from the rise and fall of the sea caused by the pull of the moon and the sun, which will not run out. Option C is wrong as an answer because biomass is agricultural residue, dung and other plant matter, which grows again each season and is therefore renewable, though it must be used no faster than it regrows. Option D is wrong as an answer because geothermal energy draws on heat continuously produced within the earth, tapped in India at sites such as Puga valley and Manikaran.