Earth was formed _____ billion years ago.

It is said the earth has formed about 4.5 billion years back. How did the earth crust and atmosphere formed according to Big Bang theory?

The first cellular forms of life appeared on earth about________million years ago (mya)

The first cellular forms of life appeared on earth about________million years ago (mya)

The asteroid which is believed to have collides with earth some 65 million years ago is

The asteroid which is believed to have collides with earth some 65 million years ago is

The first non-cellular form of life could have originated ____ billion years back

The first non-cellular form of life could have originated ____ billion years back

The first non-cellular form of life could have originated ____ billion years back