The conjugate bases of Bronsted acids H₂O and HF are respectively:

1. H₃O⁺ and H₂F⁺, respectively.

2. OH^- and H₂F⁺, respectively.

3. H₃O⁺ and F^-, respectively.

4. OH^- and F^-, respectively.

Which of the following cannot act both as a Bronsted acid and as a Bronsted base?

1. $HC{O}_3^{-}$

2. ${\mathrm{NH}}_3$

3. HCl

4. $HS{O}_4^{-}$

Boric acid is an acid because its molecule:

A Lewis base among the following is:

Among the following, the correct order of acidity is:

1. HClO < HClO₂ < HClO₃ < HClO₄
2. HClO₂ < HClO < HClO₃ < HClO₄
3. HClO₄ < HClO₂ < HClO  < HClO₃
4. HClO₃ < HClO₄ < HClO₂ < HClO

Which of the following molecular hydrides acts as a Lewis acid?

1. $N{H}_3$

2. $H_{2}O$

3. $B_2{H}_6$

4. $C{H}_4$

The tendency of BF₃, BCl₃ and BBr₃ to behave as Lewis acid decreases in the sequence:

1. $BC{l}_3>B{F}_3>BB{r}_3$

2. $BB{r}_3>BC{l}_3>B{F}_3$

3. $BB{r}_3>B{F}_3>BC{l}_3$

4. $B{F}_3>BC{l}_3>BB{r}_3$