Out of the following, which one is correct about the law of liquid pressure ?

1. Pressure is different in all directions about a point inside the liquid.
2. In a stationary liquid, pressure is different at all points on a horizontal plane.
3. Inside the liquid, pressure decreases with an increase in depth from its free surface.
4. It increases with an increase in the density of the liquid.

The pressure P₁ at a certain depth in river water and P₂ at the same depth in sea water are related as:

1. P₁ > P₂
2. P₁ = P₂
3. P₁ < P₂
4. P₁ - P₂ = atmospheric pressure

The wall of a dam is made thicker at the bottom because :

1. the pressure exerted by a liquid remains the same with its depth
2. the pressure exerted by a liquid decreases with its depth
3. the pressure exerted by a liquid increases with its depth
4. of safety from outer forces.

Hydraulic machines work on the principle of :

1. Newton's first law
2. Newton's third law
3. Pascal's law
4. both (a) and (b)