Within how many days can an appeal be made to the Supreme Court by a person aggrieved by a decision of the National Green Tribunal?

The correct answer is A, National Green Tribunal. The National Green Tribunal was set up under the National Green Tribunal Act of 2010 to settle cases on the environment, forests, water, air and biodiversity quickly, and India thus became one of the first countries in the world to create a special court of this kind. Its principal bench sits at New Delhi, with other benches at Bhopal, Pune, Kolkata and Chennai, and it is expected to dispose of a case within six months of filing. The Tribunal is not bound by the Code of Civil Procedure and follows the principles of natural justice, applying the polluter pays principle, the precautionary principle and the idea of sustainable development. It can order compensation, restoration of the environment and the closing of a polluting unit. B, C and D are wrong because they are invented expansions; no body of any of those names exists, and the word in the title is Tribunal, a court-like body, not Tribe. Exam tip: NGT Act 2010, principal bench New Delhi, cases to be decided in six months.

The correct answer is B, Haryali. Haryali is a centrally sponsored watershed development project launched in 2003 by the Ministry of Rural Development, and its whole point is that the village panchayat plans and carries out the work itself. Under it gram panchayats build check dams, farm ponds, percolation tanks and contour bunds so that rain is held where it falls; wells recharge, and dryland farmers get water for a second crop. The watershed committee is chosen by the gram sabha, and the villagers share part of the cost and the upkeep of the structures. A is wrong because the Arvary Pani Sansad is a people's parliament of villages on the Arvari river in Alwar, Rajasthan, a community effort and not a central scheme. C is wrong because Jal Kranti Abhiyan was a later water awareness campaign of the water resources ministry. D is wrong because Neeru-Meeru was a state water conservation programme of Andhra Pradesh. Exam tip: Haryali 2003, central and panchayat-led; Neeru-Meeru is Andhra Pradesh; Arvari Pani Sansad is Rajasthan.

The correct answer is D, 20°C. An ocean thermal energy conversion plant works only where the warm surface water is at least about 20 degrees Celsius hotter than the cold water drawn from the depths.

OTEC uses that difference as its heat source. The warm surface water boils a liquid with a low boiling point, such as ammonia, and the vapour turns a turbine to make electricity; cold water pumped up from roughly a kilometre down condenses the vapour back to liquid so the cycle repeats. The gap of 20 degrees is needed because a smaller one leaves too little energy to run the pumps and still send power out. Such conditions are found in tropical seas, and India has tested OTEC near the Lakshadweep and Andaman islands.

Option A is wrong because a 40 degree gap does not occur between the surface and the deep sea. Option B is wrong because 250 degrees belongs to a furnace, not the ocean. Option C is wrong because 50 degrees is far beyond any natural ocean difference.

Exam tip: OTEC needs a surface to deep water difference of about 20°C and works best in tropical waters.

The correct answer is B, hydrofluorocarbons. Hydrofluorocarbons were adopted as substitutes for chlorofluorocarbons in refrigeration and air conditioning because they do not harm the ozone layer, but they turned out to be very powerful greenhouse gases, so the Kigali Amendment of 2016 brought them under the Montreal Protocol with a schedule for reducing their use. Option A is wrong because chlorofluorocarbons were covered by the original protocol of 1987 and their production has already been phased out under it. Option C is wrong because sulphur dioxide, the main cause of acid rain, is controlled by national air quality laws and emission standards, not by this treaty. Option D is wrong because methyl bromide, used to fumigate soil, is also part of the original list of ozone depleting substances. The point being tested is that Kigali deals with a climate gas through an ozone treaty.

The correct answer is C, 16 September. The day marks the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987 and is observed every year with a theme announced by the United Nations. Option A is wrong because the fifth of June is World Environment Day, which marks the opening of the Stockholm Conference of 1972. Option B is wrong because the twenty second of April is Earth Day. Option D is wrong because the second of December is observed in India as National Pollution Control Day, in memory of the Bhopal gas tragedy of 1984. Environment sections regularly place these four dates in one question, so learn them as a set along with the twenty second of May for biological diversity and the second of February for wetlands.