For Na⁺, Mg²⁺, F^- and O^2-; the correct order of increasing ionic radii is :

Which of the following is a Lewis acid?

In the molecular orbital diagram for the molecular ion, N₂⁺, the number of electrons in the $$\sigma $$_2pz molecular orbital is :

Ejection of the photoelectron from metal in the photoelectric experiment can be stopped by applying 0.5 V when the radiation of 250 nm is used. The work function of the metal is :