name any force which cannot be expressed in vector form and also give its math. expression?

Answer 1

Force is defined as a vector quantity. It must be a vector or it is not a true force.

F = dp/dt (where p is momentum given by p = mv and v is a velocity vector)
F = ma where a is acceleration, also a vector.

The only "force" which is not a true force but a result of inertia, is centrifugal force. See the links below:

Answer 2

Love = 1+1

Answer 3

Try the force which prevents fermions from occupying the same quantum states:
http://en.wikipedia.org/wiki/Exchange_force