Q129 / 200 · MHT CET - Medical 2026 (23 April Shift 1) · Chemistry
Which of the following statements regarding inert gases is NOT true?
- AThe ionization enthalpy of each inert gas is the highest in its period.
- Correct answerBInert gases have large negative values of electron gain enthalpy
- CInert gases have very low melting and boiling points.
- DAll inert gases are monoatomic in nature.
Solution
Inert gases have completely filled valence shell electron configurations ($ns^2 np^6$, except He which is $1s^2$).
Due to this highly stable configuration, they have no tendency to accept an additional electron. If an electron is added, it must enter the next higher principal quantum shell, which leads to a highly unstable state.
Therefore, energy must be supplied to add an electron, resulting in large positive values of electron gain enthalpy, not negative.
The other statements are correct: they have the highest ionization enthalpy in their respective periods, very low melting and boiling points due to weak London dispersion forces, and are monoatomic.
Answer: Inert gases have large negative values of electron gain enthalpy
Due to this highly stable configuration, they have no tendency to accept an additional electron. If an electron is added, it must enter the next higher principal quantum shell, which leads to a highly unstable state.
Therefore, energy must be supplied to add an electron, resulting in large positive values of electron gain enthalpy, not negative.
The other statements are correct: they have the highest ionization enthalpy in their respective periods, very low melting and boiling points due to weak London dispersion forces, and are monoatomic.
Answer: Inert gases have large negative values of electron gain enthalpy
Hence, the correct answer is option: 'B'.