Which of the following is a tidal port?

The correct answer is A. The census is taken under the Census Act of 1948 by the Office of the Registrar General and Census Commissioner of India, which works under the Ministry of Home Affairs, and census is a Union subject so the responsibility is wholly that of the central government. Option B is wrong because the National Statistical Office conducts sample surveys such as the periodic labour force survey and compiles national income, which are different exercises from a complete head count. Option C is wrong because the Representation of the People Act and the Election Commission deal with electoral rolls and the conduct of elections; an electoral roll counts voters, not the whole population. Option D is wrong on both counts, because there is no Census Act of 1961 and the Planning Commission, replaced in 2015, prepared plans rather than taking the census.

The correct answer is C, 1921. It is the only census year in which the population of India actually declined, the cause being the influenza epidemic of 1918 along with famine and outbreaks of plague and cholera. After 1921 the death rate began to fall while the birth rate stayed high, so the population grew steadily, and the year therefore divides the phase of stagnant growth from the phase of steady growth. Option A is wrong because 1901 shows slow growth but no decline. Option B is wrong because 1911 also records growth, though a small one. Option D is wrong because 1951 is called the small divide, the year after which growth became very rapid and India entered the stage of population explosion. Learn the pair: 1921 the Great Divide and 1951 the small divide.

The correct answer is B, Sikkim, whose population in Census 2011 was about 6.1 lakh, the smallest of any state; among the union territories the smallest was Lakshadweep with about 64,000 people. Option A is wrong because Goa, with about 14.6 lakh people, is the smallest state of India in area but not in population. Option C is wrong because Mizoram, with about 10.9 lakh, stands above Sikkim. Option D is wrong because Nagaland, with about 19.8 lakh, is larger still, although it is remembered as the only state whose population fell between 2001 and 2011. The counterpart fact is that Uttar Pradesh is the most populous state with about 19.98 crore people, which is more than the population of most countries of the world.

The correct answer is A, Kerala, with a literacy rate of 93.91 per cent, the highest among the states, the result of a long history of schooling, missionary and princely state education and high female literacy. Option B is wrong because Mizoram, at about 91.58 per cent, stood second among the states and is the most frequent distractor in this question. Option C is wrong because Goa, at about 88.70 per cent, comes after Mizoram and Tripura. Option D is wrong because Tripura recorded about 87.22 per cent in 2011. Among the union territories Lakshadweep had the highest literacy at about 92.28 per cent, so a question that includes union territories may have a different answer from one that asks only about states. The lowest literacy among states was in Bihar at 61.80 per cent, and Kerala also has the highest sex ratio, 1,084.

The correct answer is C, Arunachal Pradesh, which recorded only 17 persons per square kilometre, the lowest among the states, because most of its area is steep mountain and dense forest with very little cultivable land. Option A is wrong because Sikkim, although the least populous state in absolute numbers, has a density of about 86 persons per square kilometre, which is far above Arunachal Pradesh; the difference between least populous and least dense is the trap here. Option B is wrong because Mizoram has a density of about 52. Option D is wrong because Himachal Pradesh, in spite of its mountains, has about 123 persons per square kilometre because of its well populated valleys. Keep the pair in mind: Bihar is the most densely peopled state and Arunachal Pradesh the least, while Uttar Pradesh is the most populous and Sikkim the least.