Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Why does a gun recoil when a bullet is fixed.

Why do we feel cooler under the fan?

Why does a ray of light bend when it travels from one medium into another?

Why does an object float or sink when placed on the surface of water?

Why does a pilot not fall down when his aeroplane takes .a vertical loop?

Why does a needle float on clear water, but sinks when some detergent is added to water?

How does our body respond when adrenaline is secreted into the blood?

Why does a piece of red glass when heated and taken out glow with green light?

GIVE REASONS - WHY : Objects are not seen clearly when we enter from bright light to a room with dim light.