Assertion (A): The atmosphere is the most dynamic entity on the earth's surface.

Reason (R): Large masses of air are being moved up and down and across the surface of the earth.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

The composition of the atmosphere makes it a dynamic entity, however there are four thermal layers. Which of the following is in the correct order from the surface of the earth?

1. Thermosphere - Mesosphere - Stratosphere - Troposphere
2. Troposphere - Mesosphere - Stratosphere - Thermosphere
3. Troposphere - Stratosphere - Mesosphere - Thermosphere
4. Thermosphere - Stratosphere - Mesosphere - Troposphere

………….. extends up to a height of about 400 km and is responsible for enabling radio communication.

1. Mesosphere
2. Ionosphere
3. Stratosphere
4. Troposphere

The upper limit of the stratosphere is known as:

1. Stratopause
2. Statapause
3. Upper strata
4. Upper limital strata