Two types of changes occur around us in our everyday life and they are termed Physical and Chemical Changes.

Physical change is a change that can be reversed and it is only responsible for the change in the shape, size, and appearance and not its composition. In a Physical Change, no new substances are formed. 

Whereas, on the other hand, a chemical change is a change that cannot be reversed and is responsible for the complete change in an object's composition as well along with the change in colour, shape, and size. In a Chemical Change, new substances are formed.

So based on this theory:

a) Photosynthesis is a chemical change because in this process new substances are formed, i.e., food and water are broken down in the presence of sunlight and it cannot be reversed.

b) Burning of coal is a chemical change because in this process coal is burnt into ashes giving out Carbon Dioxide gas and it cannot be reversed.

c) Digestion of food is a chemical change because in the process food is broken down in the form of energy releasing ATP and it cannot be reversed.

d) Melting of wax is a physical change because in this process now new substance is formed.

e) Beating of Aluminium into a thin sheet is also a physical change because only the shape and size of Aluminium are changing and can be reversed.

f) Dissolving sugar in water is a physical change because it can be reversed by evaporating the water after which only sugar will be left.

Hence, the given statement is true.