Which of the following reagents are used to give blue ring test of solution of ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$ ?

 

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{MoO}}_4$ and conc.${\mathrm{H}}_2{\mathrm{SO}}_4$ are reagents are used to give blue ring test of solution of ${\mathrm{Na}}_2{\mathrm{S}}_2{\mathrm{O}}_3$.

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{MoO}}_4+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{MoO}}_3+{\mathrm{H}}_2\mathrm{O}+{\left({\mathrm{NH}}_4\right)}_2{\mathrm{SO}}_4$

Hence, the correct option is a, c.