Question

question ①
what is the formula for chromous acid?
answer
$ce{h_{2}cr_{2}o_{7}}$
$ce{hcro_{3}}$
$ce{h_{2}cro_{4}}$
$ce{h_{2}cro_{3}}$
i dont know yet

Explanation:

Chromous acid contains chromium in the +2 oxidation state. The chromous ion is $\text{Cr}^{2+}$, and to form a neutral acid with $\text{H}^+$ ions, the formula balances the charges: two $\text{H}^+$ ions pair with one $\text{CrO}_2^{2-}$ (chromite) ion, resulting in $\text{H}_2\text{CrO}_2$. The other options correspond to chromium in higher oxidation states: $\text{H}_2\text{Cr}_2\text{O}_7$ is dichromic acid (+6), $\text{HCrO}_3$ is a hydrogen chromate species (+6), $\text{H}_2\text{CrO}_4$ is chromic acid (+6).

Answer:

$\text{H}_2\text{CrO}_2$