Which of the following is not a Lewis acid?

$Cl^-$ is the conjugate base of .....

Conjugate acid of $HPO_4^{2-}$ is

Which of the following species can act as a Bronsted-Lowry acid as well as a Bronsted-Lowry base?

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R:$
Assertion $A :$ The amphoteric nature of water is explained by using Lewis acid/base concept.
Reason $R :$ Water acts as an acid with $NH_{3}$ and as a base with $H_{2}S$.
In the light of the above statements,choose the correct answer from the options given below:

Identify the amphoteric species among the following:
$(I) \, H_2O$
$(II) \, NH_2^-$
$(III) \, H_2PO_4^-$
$(IV) \, HCO_3^-$