sentences: chocolate is a kind of solid usually & chocolate is a kind of substance ->  chocolate is a kind of solid substance  chocolate is a kind of solid substance & matter in the solid phase has definite shape ->  chocolate in solid state will have definite shape  melting means matter / a substance changes from a solid into a liquid by increasing heat energy & chocolate melts in the sunlight ->  chocolate changes from a solid to a liquid when it melts  chocolate changes from a solid to a liquid when it melts & matter in the liquid phase has variable shape ->  melted chocolate will have variable shape  chocolate in solid state will have definite shape & melted chocolate will have variable shape -> the shape of the chocolate changes when the chocolate melts