Question

In HS^-,I^-,R–NH₂, NH₃ order of proton excepting tendency will be :-

• A. I^- > NH₃ > R–NH₂ > HS^-
• B. NH₃ > R-NH₂ > HS_- > I^-
• C. RNH₂ > NH₃ > HS^-> I^-
• D. HS^-> RNH₂ > NH₃ > I^-

Answer 1

The Correct Option is C

To determine the order of proton accepting tendency for the given species—HS^-, I^-, R–NH₂, and NH₃—we need to consider their basicity. Basicity refers to the tendency of a molecule or ion to accept protons, and it's directly related to the strength of a base.

1. R–NH₂ and NH₃ are amines and ammonia, respectively. Amines (R–NH₂) generally have stronger basicity than ammonia due to the presence of an alkyl group that increases electron density on the nitrogen, enhancing its ability to accept protons.
2. NH₃ is a weaker base compared to most amines, but it still has a higher proton accepting tendency than simple ions like HS^- and I^-.
3. HS^- is the conjugate base of a weak acid H₂S, which means it has a moderate tendency to accept protons but less so than NH₃ or amines.
4. I^- is the conjugate base of a strong acid (HI), which makes it a very weak base with low proton accepting tendency.

Based on this understanding, the order of proton accepting tendency from most to least is:

RNH₂ > NH₃ > HS^- > I^-

Therefore, the correct answer is:

RNH₂ > NH₃ > HS^- > I^-