$1\, g$ of a carbonate $(M_{2}CO_{3})$ on treatment with excess $HCl$ produces $0.01186\, mol$ of $CO_{2}.$ The molar mass of $M_{2}CO_{3}$ in $g\, mol^{-1}$ is:

$20 \ g$ of iron pyrite,$FeS_2$,is roasted completely and the $SO_2$ gas produced is absorbed completely in $400 \ mL$ of $NaOH$ solution. If only $50\%$ of the $NaOH$ is used in the reaction,what was the molarity of the $NaOH$ solution?

If isobutane and $n$-butane are present in a gas,then how much oxygen should be required for complete combustion of $10 \ kg$ of this gas? (in $kg$)

$A$ gaseous mixture contains $50\%$ Helium and $50\%$ Methane by volume. What is the percentage of Methane by weight in the mixture?

How many grams of dibasic acid (mol. wt. $200$) should be present in $100 \ mL$ of its aqueous solution to give decinormal strength?

$A$ solution of $20.2 \, g$ of $1,2$-dibromopropane in $MeOH$ upon heating with excess $Zn$ produces $3.58 \, g$ of an unsaturated compound $X$. The yield $(\%)$ of $X$ is closest to [Atomic weight of $Br$ is $80$].