Question

Circle the harder of the pair of Lewis acids or bases below:
a). Ag+        K+              

b). Br-          I-                      

c). OH₂ SH₂

d). BF₃ B(CH₃)₃

e). Mo²⁺ Mo⁶⁺

Answer 1

According to me (e) is the correct answer

Because in option (a) we Ag+ which is soft acid and we have K+ which is hard acid

In option (b) we have Br- which is borderline base and I- is a soft base

In option (c) we have H2O which is a hard base and we have H2S which is a soft base.

In option (d) we have BF3 which is a hard acid and B(CH3)3 which is a borderline acid

So we are left here with option (e) only so correct answer should be (e). as Mo2+ and Mo6+ both are hard acids.