The increasing order of pK b value of the following is: (I) OH ⊖ (II) F ⊖ (III) N ⊖ H 2 (IV) C ⊖ H 3

Question

The increasing order of pK b ​ value of the following is: (I) OH ⊖ (II) F ⊖ (III) N ⊖ ​ H 2 ​ (IV) C ⊖ ​ H 3 ​

TestHub · Accepted Answer

Question Explanation: The question asks for the increasing order of $p K_{b}$ values for the given conjugate bases.

Concept: This question is based on basic strength.

Solution: The $p K_{b}$ value is inversely proportional to basicity ( $K_{b}$ ).

Basic strength $\propto$ K $_{b}$ $\propto \frac{1}{p K _{b}}$

Basic strength $\propto \frac{e l ec t ro n d e n s i t y}{e l ec t ro n e g a t i v i t yo fd o n or a t o m}$

The $K_{b}$ order is: (IV) CH₃⁻ > (III) NH₂⁻ > (I) OH⁻ > (II) F⁻

Therefore, the $p K_{b}$ order will be: (IV) CH₃⁻ < (III) NH₂⁻ < (I) OH⁻ < (II) F⁻

Final Answer: Option (A)

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