Question

First ionisation enthalpy values of the first four group 15 elements are given below. Choose the correct value for the element that is a main component of the apatite family:

• A. 1012 , \(\text{kJ mol}^{-1}\)
• B. 1402 , \( \text{kJ mol}^{-1}\)
• C. 834 , \( \text{kJ mol}^{-1}\)
• D. 947 , \( \text{kJ mol}^{-1}\)

Hint:

The ionization enthalpy increases across a period as the effective nuclear charge increases, but it decreases down a group due to an increase in atomic size. Phosphorus is a key element in the apatite family and has a relatively moderate ionization enthalpy.

Answer 1

The Correct Option is A

The apatite family is composed of minerals that are mainly made of phosphate ions, and one of the key elements in this family is phosphorus. Phosphorus is the element in Group 15, and its ionization enthalpy is \( 1012 \, \text{kJ mol}^{-1} \). Hence, the correct value corresponds to the ionization enthalpy of phosphorus.
Thus, the correct answer is \( \boxed{(1)} \).