Question

a glass stopper has got stuck in the neck of a bottle. It can be removed by pouring hot water on the neck of the bottle . Explain why

Answer 1

Hello, as you might be aware, certain materials expand on being heated, plastic being one of them. So when we pour hot water in the bottle, the glass stopper comes out freely

Answer 2

This is because when we pour hot water on the neck of the glass bottle, the heat energy from the water is transferred to the bottle neck. The molecules of the glass recieve energy and do work against the forces of attraction acting on them. As a result, the intermolecular space increases and the glass expands. This is known as thermal expansion which is due to heat. Now, the cork can be removed easily.