Assertion: The increase in internal energy `(DeltaE)` for the vaporisation of 1 mole of water at 1 atm and `373K` is zero.
Reason: For all isothermal processes `DeltaE=0` .

Options

A. If the both assertion and reason are true and the reason is the correct explanation of the assertion
B. If both assertion and reason are true and the reason is not the correct explanation of the assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false statements.

Answer

A

Explanation

At 373 K or `100^@c` the water starts boiling and at this temperature the vaporization of water is an isothermal process.
The internal energy change `(DeltaE)`, depend only on temperature, it follows that at constant temperature, the internal energy of the gas remains constant, i.e. `DeltaE` is zero.