Question

give reason for the following :-force of friction is called a contact force​

Answer 1

Answer:

this is because it only acts when two bodies are in contact to each other

Answer 2

$\purple \: answer$

Friction is a surface phenomenon. When two surfaces have irregularities that come in contact they get interlocked preventing them from sliding against each other. So, the frictional force is a contact force dependent on the surface.