Into how many culture worlds did Russell and Kniffen divide the world?

Who wrote 'Cultural Geography: An Evolutionary Introduction to Our Humanized Earth' (1969), dividing the world into culture worlds and realms?

Which school of geographical thought holds that nature offers many possibilities and man is free to choose among them?

Which Indian language is spoken maximum in the world after Hindi?

In India classification of cities on the basis of size of population are in how many categories?

Which year is called the great demographic divide in India?