By how much time day would have been shorter if the earth had no atmosphere ?

What would have been the colour of the sky, had there been no atmosphere ?

What would have been the colour of the sky, in the absence of atmosphere ?

A : If the earth did not have an atmosphere, its average surface temperature would have been lower. R : In the absence of atmosphere, the green house effect will be absent.

A : If the earth did not have an atmosphere, its average surface temperature would have been lower. R : In the absence of atmosphere, the green house effect will be absent.

Assertion : If earth did not have atmosphere, its average surface temperature would be lower than what it is now Reason : Green house effect of the atmosphere would be absent, if earth did not have atomosphere.