White Phosphorus on reaction with concentrated NaOH solution in an inert atmosphere of CO₂ gives phosphine and compound (X). (X) on acidification with HCl gives compound (Y). The basicity of compound (Y) is :

The radius of the second Bohr orbit, in terms of the Bohr radius, a₀, in Li²⁺ is :

Hydrogen has three isotopes (A), (B) and (C). If the number of neutron(s) in (A), (B) and (C) respectively, are (x), (y) and (z), the sum of (x), (y) an (z) is :

Preparation of Bakelite proceeds via reactions.