Question

A change in the physical state can be brought about:

• A. only when energy is given to the system
• B. only when energy is taken out from the system
• C. when energy is either given to, or taken out from the system
• D. without any energy change

Answer 1

Answer: (C)

when energy is either given to, or taken out from the system

A change in a physical state can be brought about when energy is either given to or taken out from the system.

For example, if we give energy or heat to ice, it will convert to liquid water similarly if we took out the energy (or cool it) from the water it will convert back to ice.

Therefore, the correct option is ($C$).