Which salt can furnish $H^{+}$ ion in its aqueous solution?

In the reaction $HNO_3 + HF \to H_2NO_3^+ + F^-$,which species acts as a base?

The conjugate base of $NH_{3}$ is

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

Consider the following reaction involving two acids shown below: formic acid and $HF$.
$K^+F^- + HCOOH \rightleftharpoons HCOO^-K^+ + HF$
Given: $pK_a$ of $HCOOH = 3.8$ and $pK_a$ of $HF = 3.2$.
Which of the following statements about this reaction are true?
$(A)$ Formic acid is the strongest Bronsted acid in the reaction
$(B)$ $HF$ is the strongest Bronsted acid in the reaction
$(C)$ $KF$ is the strongest Bronsted base in the reaction
$(D)$ $KO_2CH$ is the strongest Bronsted base in the reaction
$(E)$ The equilibrium favours the reactants
$(F)$ The equilibrium favours the products
$(G)$ Formic acid has a weaker conjugate base
$(H)$ $HF$ has a weaker conjugate base

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