What is the decreasing order of basic strengths of $\mathrm{OH}^{-}, \mathrm{NH}_{2}^{-},…

What is the decreasing order of basic strengths of $\mathrm{OH}^{-}, \mathrm{NH}_{2}^{-}, \mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}$ and $\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-}$
  1. $\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-}>\mathrm{NH}_{2}^{-}>\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{OH}^{-}$
  2. $\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{CH}_{3} \mathrm{CH}_{2}^{-}>\mathrm{NH}_{2}^{-}>\mathrm{OH}^{-}$
  3. $\mathrm{OH}^{-}>\mathrm{NH}_{2}^{-}>\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-}$
  4. $\mathrm{NH}_{2}^{-}>\mathrm{H}-\mathrm{C} \equiv \mathrm{C}^{-}>\mathrm{OH}^{-}>\mathrm{CH}_{3}-\mathrm{CH}_{2}^{-}$

Solution

Follow Lowry Bronsted concept for conjugate pair. Acid strength follows the order $\mathrm{H}_{2} \mathrm{O}>\mathrm{C}_{2} \mathrm{H}_{2}>\mathrm{NH}_{3}>\mathrm{C}_{2} \mathrm{H}_{6}$ conjugate
base will follow the order
$\mathrm{C}_{2} \mathrm{H}_{5}^{-}>\mathrm{NH}_{2}^{-}>\mathrm{C}_{2} \mathrm{H}^{-}>\mathrm{OH}^{-}$ ,

Asked in: JEE-TOPICTESTS-CHEMISTRY

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