Assertion: A parachute descends slowly whereas a stone dropped from same height falls rapidly.

Reason: The viscous force of air on parachute is larger than that of a falling stone.

Assertion: Machine parts are jammed in winter.

Reason: The viscosity of lubricant used in machine part decreases at low temperature.

Assertion: A needle placed carefully on the surface of water may float.

Reason: A needle placed carefully on the surface of water may float due to surface tension as upward force due to surface tension balances the weight of the needle.

Assertion: The angle of contact does not depend upon the inclination of the solid in the liquid.

Reason: The angle of contact depends on cohesive and adhesive forces.

Assertion: Surface tension of liquid decreases with increase in temperature.

Reason: Cohesive force between liquid molecules increase with increase in the temperature.

Assertion: A thin stainless steel needle can lay floating on still water surface.

Reason: Any object floats when the buoyant force balances the weight of the object.

Assertion: Surface energy of an oil drop is same whether placed on glass or water surface.

Reason: Surface energy is dependent only on the properties of oil.