Question

What is the value of electron gain enthalpy of $N{a}^{+}\text{if}I{E}_1\text{of}Na=5.1\text{eV}$ ?

• A. $+2.55\text{eV}$
• B. $-10.2\text{eV}$
• C. $+0.2\text{eV}$
• D. $-5.1\text{eV}$

Answer 1

The correct option is D $-5.1\text{eV}$


The electron gain enthalpy is equal to the first ionization enthalpy of the atom but opposite in sign.

$\text{electron gain enthalpy = - first ionisation enthalpy}$
$\therefore \text{electron gain enthalpy}=-5.1\text{eV}$