Q4 How are Northern plains fertile. Give reason.

The Northern Plain was formed by the deposits brought in by the three major rivers and their tributaries. Alluvium was deposited at the foot–hills of the Himalayas for millions of years. These deposits are now the fertile Northern Plains. Alluvium is soil or sediments deposited by a river or other running water.

heat released by collision processes during accretion, and heat from decay of radioactive elements

explanation:

answer(c) carved on a babylonian clay tablet that showed earth as a flat circular disk;