Question

Which statement is false for the periodic classification of elements?

• A. The properties of the elements are the periodic functions of their atomic numbers
• B. Non-metallic elements are lesser in number than the metallic elements
• C. The first ionization energies of the elements along a period do not vary in a regular manner with increase in atomic number
• D. For transition elements, the d-electrons are filled monotonically with increase in atomic number

Answer 1

Answer: (D)

According to laws of writing electronic configuration, electrons are added one at a time to the penultimate d-orbitals but due to extra stability of $d^{5}$ and $d^{10}$ configurations, two electrons appears to have entered the d-shell due to shifting of one electron from ns to $\left(\right.n-1\left.\right)d$ orbital.
Rest other statements are correct here.