Can individual objects in a system have momentum while the momentum of the combined system is zero?

Explanation:

The above statement is true

suppose if a body of mass m is moving with speed 2v in positive x direction

and another body of mass 2 m is moving with velocity v in negative x direction

Momentum of first particle in positive x direction

Momentum of second particle in negative x direction

So combined momentum of system is zero but individual momentum is not zero                          

b.a device that inputs heat into a cool object