A mixture of $CaCO_3$ and $MgCO_3$ weighing 1.84 g on heating leaves a residue weighing 0.96 g. If the percentage by mass of $CaCO_3$ in the original mixture is x%, what is the value of x/2?

$26\,{\rm{mL}}$ of ${\rm{C}}{{\rm{O}}_2}$ are passed over hot coke. The maximum volume of CO formed is :

Which of the following statement is correct

A mixture of ${\rm{2}}{\rm{.3}}\,\,{\rm{g}}$ formic acid and ${\rm{4}}{\rm{.5}}\,\,{\rm{g}}$ oxalic acid is treated with conc. ${{\rm{H}}_{{\rm{2}}\,}}{\rm{S}}{{\rm{o}}_{\rm{4}}}$ . The evolved gaseous mixture is passed through ${\rm{KOH}}$ pellets weight (in g) of the remaining product at STP will be