Water is a

What will be the conjugate acid-base pair in the reaction $HCl_{(aq)} + H_2O_{(aq)} \rightleftharpoons H_3O^{+}_{(aq)} + Cl^{-}_{(aq)}$?

Which of the following is the weakest Bronsted-Lowry base?

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

The strongest base from the following species is

Consider the following data for a series of hydrogen halide Bronsted acids:-

Acid	$HF$	$HCl$	$HBr$	$HI$
$K_a$	$7.2 \times 10^{-4}$	$1 \times 10^6$	$1 \times 10^9$	$3 \times 10^{11}$

Which of these Bronsted acids would have the weakest conjugate base?