How much of the Indian population has Hindi as its mother tongue?

Q. A village has a population of $6000;50$ litres of water is required per person per day. The village has a water tank measuring $60m\times 30m\times 8m$ completely filled with water. For how many days the water of this tank is sufficient.

Q. A T.V. tower has a height of 100m. How much population is covered by the T.V. broadcast if the average population density around the tower is 1000 per sq.km. Radius of the earth $6.37\times {10}^{6}m$. By how much height of the tower be increased to double its coverage range?

Q. T.V. transmission tower at a particular station has a height of 160m:(a) What is its coverage range? (b) How much population is covered by transmission, if the average population density around the tower is ${1200km}^{-2}$? (c) By how much the height of tower be increased to double its coverage range? Given radius of earth = 6400km.

Q. How much is the total Indian population in 2020?

Q. In $2013$, the population of a town was recorded as $648453$. In year $2012$, its population $429315$. How much more was the population in $2013$, than year $2012$?