Energy of an electron is given by $$E = - 2.178 \times {10^{ - 18}}J\left( {{{{Z^2}} \over {{n^2}}}} \right)$$. Wavelength of light required to excite an electron in an hydrogen atom from level n = 1 to n = 2 will be
(h = 6.62 × 10⁻³⁴ Js and c = 3.0 × 10⁸ ms⁻¹)

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

The first ionization potential of Na is 5.1 eV. The value of electron gain enthalpy of Na+ will be:

Which one of the following molecules is expected to exhibit diamagnetic behaviour?