Which one of the following is the main objective of Vienna Convention and Montreal Protocol?

The correct answer is D, Tamil Nadu. Tamil Nadu is the first state in India to make rooftop rainwater harvesting structures compulsory for all houses and buildings across the state, through a law brought in 2003. The state depends heavily on the north-east monsoon and on groundwater, and Chennai faced severe water shortages, so collecting roof water and sending it into the ground became a priority. Rooftop harvesting collects rain from roofs and stores it in tanks or uses it to recharge wells and aquifers, which raises the water table. Option A is wrong because Kerala gets heavy rain and has promoted harvesting, but it was not the first to make it compulsory for every house. Option B is wrong because Gujarat is known for check dams and other water works, not for this first law. Option C is wrong because Rajasthan is known for traditional harvesting, such as the tankas of Bikaner and Phalodi, not for the first statewide law. Exam tip: Tamil Nadu was the first state to make rooftop rainwater harvesting compulsory (2003); tankas are Rajasthan's traditional underground tanks.

The correct answer is C, Jim Corbett National Park. It is India's first national park, set up in 1936 as Hailey National Park, in the Nainital area of present-day Uttarakhand. It was later called Ramganga National Park and was renamed in the 1950s in honour of Jim Corbett, the famous hunter who turned into a naturalist and wrote 'Man-Eaters of Kumaon'. Project Tiger was launched here in 1973, and the park lies along the Ramganga river in the foothills of the Himalayas. Option A is wrong because Gir in Gujarat, the last home of the Asiatic lion, became a national park only in 1975. Option B is wrong because Kaziranga in Assam, famous for the one-horned rhinoceros, became a national park in 1974. Option D is wrong because Rajaji National Park in Uttarakhand was formed in 1983 by joining three sanctuaries. Exam tip: the first national park went from Hailey (1936) to Ramganga to Jim Corbett, and Project Tiger began here in 1973.

The correct answer is D, Turbidity of water. NTU stands for Nephelometric Turbidity Unit. A nephelometer shines a beam of light through a water sample and measures how much of it is scattered sideways by suspended particles such as clay, silt, algae and microbes; the more the scattering, the more turbid, or cloudy, the water is. Turbidity is a key test for drinking water because the particles can shield germs from chlorine and other disinfectants, so water supply agencies try to keep it very low before the water reaches homes. High turbidity in a river or lake also cuts off sunlight for aquatic plants. Option A is wrong because water pressure is measured in units such as the pascal or the bar. Option B is wrong because temperature is measured in degrees Celsius or in kelvin. Option C is wrong because acidity is shown on the pH scale, where 7 is neutral and values below 7 are acidic. Exam tip: NTU = turbidity (cloudiness); pH = acidity; BOD = organic pollution, in milligrams per litre.

The correct answer is B, Marine. In the sea the producers are tiny phytoplankton. At any given moment their total mass is smaller than the mass of the zooplankton and fish that feed on them, so the pyramid of biomass stands upside down. This happens because phytoplankton grow and divide very fast and are eaten almost as quickly as they are produced, so a small standing crop can support a larger mass of consumers. The pyramid of energy, however, is always upright in every ecosystem, because energy is lost as heat at each step and only about 10 percent passes to the next level. Option A is wrong because in a grassland the grasses far outweigh the grazing animals, giving an upright pyramid. Option C is wrong because the tundra also has more plant mass than animal mass. Option D is wrong because in a forest the huge trees give a large biomass base, so the pyramid of biomass is upright, even though the pyramid of numbers there can be inverted. Exam tip: numbers can be inverted in a tree ecosystem, biomass in the sea, but energy never.

The correct answer is B, Cadmium pollution. Itai-itai disease is long-term cadmium poisoning, first noticed around 1912 in the Toyama region of Japan, where mines upstream released cadmium into the Jinzu river and it built up in the rice and water used by villagers. Cadmium damages the kidneys and makes bones soft and brittle, so patients suffered repeated fractures and severe pain in the spine and joints; the name means it hurts, it hurts in Japanese. It became one of the four big pollution diseases of Japan. Option A is wrong because mercury pollution causes Minamata disease, also from Japan, which spread through eating fish from a bay polluted with methylmercury. Option C is wrong because arsenic in groundwater causes arsenicosis, with skin lesions and cancers, as seen in West Bengal and Bangladesh. Option D is wrong because too much nitrate in drinking water causes blue baby syndrome, or methaemoglobinaemia, in infants. Exam tip: cadmium–itai-itai, mercury–Minamata, nitrate–blue baby, fluoride–fluorosis.