Answer
a. Acid
b. Salt
c. Base
d. Salt
Work Step by Step
1. Divide the compound in ions.
a: $H^+$ and $NO{_2}^-$
b. $Mg^{2+}$ and $Br^-$
c. -*
d. $Li^+$ and $SO{_3}^{2-}$
* $NH_3$ is an exception.
c. According to the table 11.4 (Page 412) $NH_3$ is a base, and its $K_b$ is $1.8 \times 10^{-5}$
2.
If there is a $H^+$ in it, the compound is an acid.
If there is a $OH^-$ in it, the compound is a base.
If it does not have $H^+$ and $OH^-$, it is a salt.
