Which of the following statements are correct for classification of elements?
I. The properties of elements are periodic functions of their atomic numbers.
II. Non-metallic elements are less in number than the metallic elements.
III. The first ionisation energies of elements along a period do not vary in a regular manner.
IV. The ground state electronic configuration of \(\mathrm{Pd}(Z=46)\) is \([\mathrm{Kr}] 4 d^8 5 s^2\).

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.