Q.The year 1961 in population is known as the ______.

Density of population = Total population divided by the land area of the region, so the answer is option (a).

Density of population tells us how thickly or thinly a region is populated. It is defined as the number of persons living per unit of land area (usually per square kilometre):

Density of population = Total population / Land area of the region

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The population turning point being asked about is termed the 'Year of Great Divide', so the answer is option (c).

In the demographic history of India taught in the Tamil Nadu HSC Class-11 Economics syllabus, two census landmarks are named:

• The Year of Great Divide (1921) — before 1921 India's population growth was slow and irregular (with actual declines in some decades due to famines and epidemics); after 1921 the population began to increase continuously. Hence 1921 is called the year of the Great Divide. …

The correct option is (a) Fifth: India ranks fifth by economy size.

Measured by the size of its Gross Domestic Product, the Indian economy ranks fifth among the largest/strongest economies of the world, having overtaken several developed nations in aggregate output while still being a developing economy in per-capita terms.

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The year 1951 is called the "Year of the Small Divide" in India's demographic history.

India's population growth is studied through landmark census years:

• 1921 — Year of the Great Divide: up to 1921 population had grown slowly and even fallen in some decades due to famines and epidemics; after 1921 it began to increase continuously, marking a major turning point. …

The co-existence of two different features in an economy is called dualism.

Dualism refers to the presence of two sharply contrasting sets of conditions within the same economy — for example, a modern, technologically advanced sector existing side by side with a backward, traditional sector; or an organised sector alongside an unorganised one. This technological and economic dualism is a typical characteristic of developing economies like Indi …

France is a developed nation.

Developed nations are marked by high per-capita income, advanced industrialisation, a large tertiary sector, high levels of technology and a high standard of living. France meets all these criteria. Mexico, Sri Lanka and Ghana, in contrast, display features of developing economies — lower per-capi …

The 'Year of Small Divide' is (b) 1951.

In the demographic history of India, the year 1921 is famous as the 'Year of Great Divide' because up to 1921 the population grew slowly and erratically, but after 1921 it began to increase steadily and rapidly. The year 1951 marks a further, smaller turning point in this growth pattern and is therefore referred to as the 'Year of Small Divide', as the pace of population growth changed again around that census.

Why the others are wrong: …