The species among the following,which can act as an acid and a base is

Which of the following cannot act as a Lewis or Bronsted acid?

Which of the following species acts as a base,according to the Bronsted-Lowry theory?
$HCl + NH_3 \rightleftharpoons NH_4^+{_{\text{(aq)}}} + Cl^-{_{\text{(aq)}}}$

The total number of diprotic acids among the following is:
$H_3PO_4, H_2SO_4, H_3PO_3, H_2CO_3, H_2S_2O_7, H_3BO_3, H_3PO_2, H_2CrO_4, H_2SO_3$

Identify the conjugate base of $[Zn(H_2O)_4]^{2+}$ from the following:

Cis-butene dioic acid $\overset{K_{a_1}(-H^+)}{\longleftrightarrow} X_1^- \overset{K_{a_2}(-H^+)}{\longleftrightarrow} X_2^{2-}$
Trans-butene dioic acid $\overset{K'_{a_1}(-H^+)}{\longleftrightarrow} Y_1^- \overset{K'_{a_2}(-H^+)}{\longleftrightarrow} Y_2^{2-}$
The incorrect statement regarding the above information is: