EXPLAIN EACH STEP IN DETAIL WRONG OPTIONS ALSO CORRECT ANSWER IS A

The correct sequence of reagents for the

preparation of $Q$ and $R$ is :

$(1)($i$)C{r}_2{O}_3,770K,20$atm;

$($ii$)Cr{O}_{2}C{l}_2,H_3{O}^{+}$;

$($iii$)$ NaOH;

$($iv$)H_3{O}^{+}$

$(2)($i$)Cr{O}_{2}C{l}_2,H_3{O}^{+}$;

$($ii$)C{r}_2{O}_3,770K,20$atm;

$($iii$)$ NaOH; $($iv$)H_3{O}^{+}$

$(3)($i$)KMn{O}_4,O{H}^{-}$; $($ii$)M{o}_2{O}_3,A$; $($iii$)$ NaOH;

$($iv$)H_3{O}^{+}$

$(4)($i$)M{o}_2{O}_3,$; $($ii$)Cr{O}_{2}C{l}_2,H_3{O}^{+}$; $($iii$)$ NaOH;

$($iv$)H_3{O}^{+}$