Assertion (A): The thickness of the atmosphere is maximum over the Equator. Reason (R): High insolation and strong convection currents occur over the Equator.

Answer: (a) Both A and R are individually true and R is the correct explanation of A

Strong heating and convection push the troposphere highest at the equator.

The idea

Strong heating expands tropical air and drives deep convection. This raises the tropopause, the upper boundary of the troposphere. The question’s broad word “atmosphere” is best understood here as the thickness of the lower weather layer. The whole atmosphere has no single sharp outer edge comparable to the tropopause.

High tropical insolation → Surface and lower air warm → Warm air expands and rises → Convection carries heat higher → Tropopause stands higher over the equatorial region

Why the others are wrong

(b) R explains A.

(c) R is true.

(d) A is true.

Also know

The tropopause is generally lower over the poles and changes with season. The stratosphere above it contains the ozone-rich region. The thermosphere expands and contracts with solar activity, a different control from surface convection. Atmospheric pressure measures the weight of air above a place, not the height of one layer alone.