Step-by-step explanation:
According to collision theory, more is the number of collisions taking place in a reaction faster will be its rate of reaction.
Hence, when we add sugar in hot tea then due to high temperature of tea, molecules of sugar will gain kinetic energy and more number of collisions will take place between its molecules.
As a result, sugar will readily dissolve in hot tea.
On the other hand, cold tea will have low temperature due to which molecules of sugar will not gain any kinetic energy. Hence, there will occur no collisions between particles of sugar.
As a result, rate of reaction will not be fast.