Pressure exerted by a liquid is due to its:

1. weight
2. mass
3. volume
4. area

Pressure inside a liquid increases with:

1. increase in depth.
2. decrease in depth.
3. decrease in density.
4. none of the above.

Nose bleeding may occur at a high altitude because:

1. the atmospheric pressure decreases.
2. the oxygen content of atmosphere decreases.
3. the atmospheric pressure increases.
4. there are strong air currents at the high altitude.

Define force. State its S.I. unit.