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

The stoichiometric reaction of $516 \ g$ of dimethyldichlorosilane with water results in a tetrameric cyclic product $X$ in $75 \%$ yield. The weight (in $g$) of $X$ obtained is. . . . . . . [Use,molar mass $(g \ mol^{-1})$: $H=1, C=12, O=16, Si=28, Cl=35.5$]

What is the value of $w$ (mass of solute in grams) required to prepare a definite volume of a standard solution of known normality $(N)$?
[$N = \text{normality}$,$E = \text{equivalent weight}$,$V = \text{volume of solution in } mL$]

$1.84 \ g$ of a mixture of $CaCO_3$ and $MgCO_3$ is strongly heated to get a residue of $0.96 \ g$. The percentage of $CaCO_3$ in the mixture is

The ratio of the molar amounts of $H_2S$ needed to precipitate the metal ions from $20 \ mL$ each of $1 \ M \ Cd(NO_3)_2$ and $0.5 \ M \ CuSO_4$ is

If an $LPG$ cylinder contains a mixture of butane and isobutane,what is the amount of oxygen required for the combustion of $1 \ kg$ of this mixture in $kg$?