Test: Main Group - 2 - Chemistry MCQ

Boron, B is smaller than beryllium, Be atom. Hence we expect increase in ionization energy from Be to B.

However, Be atom has greater ionization energy than B atom. The reason is - in case of Beryllium, the last electron is in the s-orbital and in Boron, the last electron is in the p-orbital. We know that removal of electron from s-orbital requires more energy than the electron from p-orbital.

2s²2p³ configuration is more stable than 2s²2p⁴ due to half filled p-sublevel. The electrons in the p-orbital in N atom experience less repulsion, thus more stable and more ionization energy.  Whereas in case of O atom the 4th p-electron atom can be removed more easily as it experiences more repulsion from the electrons in the p-orbitals already present.  Hence nitrogen, Oxygen atom has less ionization energy than Nitrogen atom.

Explanation : Balanced Chemical Equation 

P₄O₆ + H₂O = H₃PO₄ + PH₃

Generally, a gas behaves more like an ideal gas at higher temperature and lower pressure, as the potential energy due to intermolecular forces becomes less significant compared with the particles' kinetic energy, and the size of the molecules becomes less significant compared to the empty space between them.

Phosphorus Pentoxide, Reagent, ACS is the anhydride of phosphoric acid and a powerful dehydrating and desiccant agent. It is used extensively in organic synthesis as a dehydrating agent.

Correct Answer :- a

Explanation : The silicon containing residual hydroxyl groups will be cross linked using boric acid and this tri functional acid, B(OH)3 groups, forms Si-O-B linkage between siloxane chains.