What is the mass of oxygen in $g$ required to produce enough $CO$ for the complete reduction of $1.6 \ kg$ of $Fe_2O_3$ (molar mass $= 160 \ g/mol$)?

$A$ cylinder of gas is assumed to contain $11.2 \ kg$ of butane $(C_4H_{10})$. If a normal family needs $20000 \ kJ$ of energy per day,the cylinder will last: (Given that $\Delta H$ for combustion of butane is $-2658 \ kJ/mol$)....$days$

What is the value of percent atom economy if the formula weight of the product is $46 \ u$ and the sum of the formula weight of all reactants is $92 \ u$ (in $\%$)?

$0.43 \ g$ of a metal of valence $2$ was dissolved in $50 \ mL$ of $0.5 \ M \ H_2SO_4$ solution. The unreacted acid required $14.2 \ mL$ of $1 \ M \ NaOH$ solution for neutralization. The atomic weight of the metal is: (in $u$)

The chloride of a metal has the formula $MCl_3$. The formula of its phosphate will be

According to the reaction,$Mg_{(s)} + 2HCl_{(aq)} \longrightarrow MgCl_{2_{(aq)}} + H_{2_{(g)}} \uparrow$,calculate the mass of $Mg$ required to liberate $4.48 \ dm^3$ of $H_2$ gas at $STP$. (Molar mass of $Mg = 24 \ g \ mol^{-1}$) (in $g$)