There is some liquid in a closed bottle. The amount of liquid is continuously decreasing. The vapour in the remaining part

1.  must be saturated

2.  must be unsaturated

3.  may be saturated

4.  there will be no vapour. 

There is some liquid in a closed bottle. The amount of liquid remains constant as time passes. The vapour in the remaining part:

In a room containing air, heat can go from one place to another:
1. by conduction only
2. by convection only
3. by radiation only
4. by all three modes

In summer, a mild wind is often found on the shore of a calm river. This is caused due to:

Choose the correct option from the given ones: