Question

Plain of India is home to one tenth of the worlds population

Answer 1

That statement is FALSE

Total earth population is around 7.2 Billions, meanwhile India has more than 1.2 Billion in population

India is home for more one tenth of the worlds population ( around  one sixth)

hope this helps

Answer 2

What is the world's population ? Currently, it's 7.4 billion. So 1/10th of the world's population would be 740 000 people.
There are two countries in this Plain: Bangladesh (150 million) and Pakistan (180 million) - that's in total 330 million.

Also, numerous Indian states are in this plain: Uttar Pradesh (200, 630 million so far), Bihar (100, that makes 730), Haryana (30 million, so we already have 760 million)

So the answer is true, and likely it's a little more than one tenth.