JEE MainChemistryp Block Elements (Group 15, 16, 17 & 18)
Consider the following statements regarding the changes occurring as one moves down Group 15 from NH ₃ to BiH ₃ : (I) The percentage s-character of the orbital containing the lone pair increases. (II) The reducing character of the hydrides increases. (III) The H-E-H bond angle increases. (IV) The thermal stability of the hydrides increases. Choose the correct statements from the options given below:
Options
- A(II) and (III) only
- B(I) and (II) only
- C(I) and (IV) only
- D(II) and (IV) only
Correct answer
B. (I) and (II) only
Step-by-step solution
Statement (I) is correct: In NH ₃ , the central nitrogen atom is sp^3 hybridized, and the lone pair resides in an sp^3 hybrid orbital (approximately 25 % s-character). For the heavier hydrides ( PH ₃ , AsH ₃ , etc.), Drago's rule applies; hybridization is negligible, and the bond pairs use almost pure p-orbitals. Consequently, the lone pair resides in an almost pure s-orbital (approaching 100 % s-character). Thus, the s-character of the lone pair orbital increases down the group. Statement (II) is correct: The atom