Question

What is the value of electron gain enthalpy of \( \text{Na} \), if \( \text{IE}_\text{Na} = 5.1 \, \text{eV} \)?

• A. \( -5.1 \, \text{eV} \)
• B. \( -10.2 \, \text{eV} \)
• C. \( +2.55 \, \text{eV} \)
• D. \( +10.2 \, \text{eV} \)

Hint:

Electron gain enthalpy is typically the negative of ionisation energy for metals.

Answer 1

The Correct Option is A

The electron gain enthalpy of sodium (\( \text{Na} \)) is the negative of its ionisation energy, as it involves gaining an electron. Thus, the electron gain enthalpy is \( -5.1 \, \text{eV} \), equal to the ionisation energy value for sodium.

Step 2: Conclusion.
The correct answer is \( -5.1 \, \text{eV} \), corresponding to option (a).