Two balls each with with a mass of 0.5 kg, collide on a pool table. is the law of conservation of momentum satisfied in this collision

Yes, the law of conservation of momentum is satisfied. The total momentum before the collision is 1.5 kg • m/s, and the total momentum after the collision is

1.5 kg • m/s. The momentum stays the same after the collision.

The law of conservation of momentum is applied when the net momentum is conserved i. e. the initial momentum before colliding is equal to the final momentum after the collision. Since, its not given whether its elastic collision or not. But, when the elastic collision of two bodies having same mass, takes place then the momentum is conserved.