Question

the force acting between 2 point charges q1 and q2 kept at some distance apart in air is attractive or repulsive when(1) q1q2>0 (2) q1q2<0

Answer 1

in first attractive and in second repulsive maybe

Answer 2

when q1q2 >0 it means the product of charge q1 and q2 is positive..
This implies that either q1 and q2 both are positive or they are negative as the product of two positive or two negative numbers is positive.. I.e. + × + = +. or - × - = +

So the force is repulsive in first case
as like charges repulse each other(either they both are positive or negative)

In second case the product is less than 0 which implies that the product is negative
It means either of q1 or q2 is negative and the other one is positive...
Since unlike charges attract each other so the second case is attractive.....

Hope it helps....