The correct decreasing order of basic strength of $\mathrm{H}_2 \mathrm{O}, \mathrm{NH}_3, \mathrm{OH}^{-}, \mathrm{NH}_2^{-}$is

• Correct answer
  A

  $\mathrm{H}_2 \mathrm{O}>\mathrm{NH}_3>\mathrm{OH}^{-}>\mathrm{NH}_2^{-}$
• B

  $\mathrm{OH}^{-}>\mathrm{NH}_2^{-}>\mathrm{H}_2 \mathrm{O}>\mathrm{NH}_3$
• C

  $\mathrm{NH}_3>\mathrm{H}_2 \mathrm{O}>\mathrm{NH}_2^{-}>\mathrm{OH}^{-}$
• D

  $\mathrm{NH}_3>\mathrm{H}_2 \mathrm{O}>\mathrm{OH}^{-}>\mathrm{NH}_2^{-}$

Hence, the correct answer is option: 'A'.