How many moles of $KCl$ are dissolved in $1000 \ mL$ of $3 \ M$ $KCl$ solution?

The mass of $CO_2$ that shall be obtained by heating $10 \ kg$ of $80\%$ pure limestone $(CaCO_3)$ is $:-$ (in $kg$)

In the above reaction,$3.9 \ g$ of benzene on nitration gives $4.92 \ g$ of nitrobenzene. The percentage yield of nitrobenzene in the above reaction is............. $\%$. (Round off to the Nearest Integer).
(Given atomic mass: $C : 12.0 \ u$,$H : 1.0 \ u$,$O : 16.0 \ u$,$N : 14.0 \ u$)

The amount of water produced (in $g$) in the oxidation of $1$ mole of rhombic sulphur by conc. $HNO_3$ to a compound with the highest oxidation state of sulphur is. . . . . (Given data : Molar mass of water $= 18 \ g \ mol^{-1}$)

What is the mass of potassium chloride produced when $12.25 \ g$ of potassium chlorate undergoes decomposition (in $g$)? (Atomic masses: $K=39, Cl=35.5, O=16$)

The active mass of $64 \ g$ of $HI$ in a $2 \ L$ flask is......