Question

Assign a possible reason for the following :
(a) Stability of + 5 oxidation state decreased and that of + 3 oxidation state increases down the group 15 elements.
(b) H₂O is less acidic than H₂S.
(c) SF₆ is inert while SF₄ is highly reactive towards hydrolysis.
(d) H₃PO₂ and H3PO₃ act as reducing agents while H₃PO₄ does not.
(e) Helium gas is used by scuba divers.

Answer 1

[Hint :   (a) Due to inert pair effect.
(b) Due to more bond dissociation enthalpy of O – H as compared to S – H bond.
(c) Due to more steric hindrance offered by six F in SF₆ as compared to SF₄.
(d) Due to presence of P – H bond in them.
(e) He is very less soluble in blood.]