Question

The correct decreasing order of basic strength of the following species is ______.

\[\ce{H2O, NH3, OH-, NH^{-}2}\]

Options

• \[\ce{NH^{-}2 > OH- > NH3 > H2O}\]

• \[\ce{OH- > NH^{-}2 > H2O > NH3}\]

• \[\ce{NH3 > H2O > NH^{-}2 > OH^-}\]

• \[\ce{H2O > NH3 > OH- > NH^{-}2}\]

Answer 1

The correct decreasing order of basic strength of the following species is \[\ce{NH^{-}2 > OH- > NH3 > H2O}\].

Explanation:

Due to higher electronegativity of O than N atom, \[\ce{O – H}\] bond is more polar than \[\ce{N – H}\] bond. Hence, \[\ce{O – H}\] is more acidic in nature than \[\ce{N – H}\] bond. Now, \[\ce{NH2}\] and \[\ce{OH}\] have negative charge due to which they are more basic than \[\ce{NH3}\] and \[\ce{H2O}\].