1) Pole star does not seem to change its position because it is very near to the axis of rotation of earth. But as axis of rotation of earth keeps changing, thus the current polar star would be replaced by other stars in the distant future.
2) It is due to the pressure exerted by water. As the depth of water increases, the pressure also increases.Water tanks are kept on the terrace of buildings. The distance between the tank and the upstairs tap is lesser than the distance between the tank and the downstairs tap, so water comes out with more force in the downstairs tap.
3) That is because water is a good conductor of electricity. It is a safety measure to ensure that the fire can be extinguished without causing any more damage.
4) This is because the weight would increase and frictional force also increases as it depends on weight.