Q1: A heavy ladder resting on a floor and against a vertical wall may not be in equilibrium, if

ANS:C - floor and wall both are smooth surfaces

If both the floor and the wall are smooth surfaces, it means that there is no friction present at the contact points between the ladder and either the floor or the wall. In this scenario, without friction, the ladder wouldn't be able to stay in place against the wall. The ladder would slide down due to gravity, and there would be nothing to prevent it from doing so since there is no friction to oppose the gravitational force.