Question

$X_{\left(g\right)}+e^{-}\to X_{\left(g\right)}^{-}+E$

Here, $E$ is :

• A. first electron affinity
• B. first ionisation energy
• C. second electron affinity
• D. second ionisation energy

Answer 1

Answer: (A)

first electron affinity

• The first electron affinity is defined as the change in energy (in kJ/mole) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion.
  

In the above reaction, $X$ is gaining one electron to form uninegative ion, hence, $E$ is first electron affinity of the atom.