Assertion (A) First ionisation enthalpy of oxygen is less than that of nitrogen.

Reason (R) Atoms with half-filled or completely filled orbitals are less stable.

The correct option among the following is

Tha atomic radius of gallium is less than that of aluminium. This is due to

$$ \text { Match the following. } $$

$$ \begin{array}{cccc} \hline & \begin{array}{c} \text { List-I } \\ \text { (Atomic number) } \end{array} & & \begin{array}{c} \text { List-II } \\ \text { (Group number and } \\ \text { period number) } \end{array} \\ \hline \text { A. } & 56 & \text { I. } & 9,4 \\ \hline \text { B. } & 50 & \text { II. } & 3,6 \\ \hline \text { C. } & 27 & \text { III. } & 14,5 \\ \hline \text { D. } & 58 & \text { IV. } & 2,6 \\ \hline \end{array} $$

The correct answer is

What is the correct order with respect to metallic property of Zr, Cd, Sn, Sr?