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

Which amongst the following is not a domain of the Biosphere?

1. Lithosphere
2. Exosphere
3. Hydrosphere
4. Atmosphere

The upper limit of the stratosphere is known as:

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

Assertion (A): About 90 per cent of the mass of air lies within a height of about 20 km from the surface of the earth.

Reason (R): The air of the lower layer is always heavier or denser, while the upper layers are thinner or less dense.

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.