How many grams of iron are theoretically produced by the reduction of $1 \ kg$ of $Fe_2O_3$?

Haemoglobin contains $0.33\%$ of iron by weight. The molecular weight of haemoglobin is approximately $67200$. The number of iron atoms (At. wt. of $Fe = 56$) present in one molecule of haemoglobin is

If $10 \ g$ ($90 \%$ pure) limestone is heated,what volume of $CO_2$ in liters will be obtained at $NTP$?

Amount of oxygen required for combustion of $1 \, kg$ of a mixture of butane and isobutane is ............. $kg$.

In a chemical reaction,the sum of the formula weight of all reactants is $274 \ u$ and the atom economy is $50 \%$. Calculate the formula weight of the desired product. (in $u$)

$x \ mg$ of pure $HCl$ was used to make an aqueous solution. $25.0 \ mL$ of $0.1 \ M$ $Ba(OH)_2$ solution is used when the $HCl$ solution was titrated against it. The numerical value of $x$ is . . . . . . $\times 10^{-1}$. (Nearest integer)
Given: Molar mass of $HCl$ and $Ba(OH)_2$ are $36.5$ and $171.0 \ g \ mol^{-1}$ respectively.