Question

Which of the following represents the correct order of increasing first ionization enthalpy for ${Ca}, {Ba}, {S}$, Se and Ar?

(a) ${Ca}<{Ba}<{S}<{Se}<{Ar}$

(b) ${Ca}<{S}<{Ba}<{Se}<{Ar}$

(c) ${S}<{Se}<{Ca}<{Ba}<{Ar}$

(d) ${Ba}<{Ca}<{Se}<{S}<{Ar}$

Answer 1

Ionization enthalpy increases on moving from left to right across the period as the size decreases and decreases on moving top to bottom in a group as the size increases. Ar has the maximum value of I.E., since it is a noble gas. So, the correct order of increasing first ionization enthalpy $\left(\Delta_i H_1\right)$ is

${Ba}<{Ca}<{Se}<{S}<{Ar} .$

So, The correct option of this question will be (D).