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

$5 \, mL$ of $N$ $HCl$,$20 \, mL$ of $N/2$ $H_2SO_4$,and $30 \, mL$ of $N/3$ $HNO_3$ are mixed together and the volume is made up to $1 \, L$. The normality of the resulting solution is:

Given that $N_{2(g)} + 3 H_{2(g)} \longrightarrow 2 NH_{3(g)}$; $\Delta_r H^{\circ} = -92 \ kJ$, the standard molar enthalpy of formation in $kJ \ mol^{-1}$ of $NH_{3(g)}$ is

Which of the following is the correct formula to determine percent atom economy?

$C_6H_6$ (liq) + $\frac{15}{2}O_2$ $(g)$ $\rightarrow$ $6CO_2$ $(g)$ + $3H_2O$ (liq). Benzene burns in oxygen according to the above equation. What is the volume of oxygen (at $STP$) needed for complete combustion of $39 \ g$ of liquid benzene (in $L$)?

How many $g$ of bromine will react with $21\, g$ of $C_3H_6$?