Statement A : The component of reaction (R) perpendicular to the plane of contact is called normal reaction.
Statement B : Friction always opposes the relative motion of one surface over the other surface.

Statement A : The component of reaction (R) perpendicular to the plane of contact is called normal reaction.
This statement is true. The normal reaction, often denoted by N, is the force exerted by a surface perpendicular to the surface when an object rests on it

Statement B : Friction always opposes the relative motion of one surface over the other surface.
This statement is also true. Friction is a force that opposes the relative motion or tendency of motion between two surfaces in contact. It acts in the direction opposite to the direction of motion or the direction in which motion would occur if there were no friction.