In the complete combustion of $C_4H_{10}$,the number of moles of oxygen required is:

If $1 \, mole$ of $H_3PO_x$ is completely neutralized by $80 \, g$ of $NaOH$,select the correct statement :-

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

$5.75 \ mg$ of sodium vapour is converted to sodium ion. If the ionisation energy of sodium is $490 \ kJ \ mol^{-1}$ and atomic weight is $23 \ g \ mol^{-1}$, the amount of energy needed for this conversion will be (in $kJ$)

If $10$ volumes of dihydrogen gas react with $5$ volumes of dioxygen gas, how many volumes of water vapour would be produced?

What is the normality of $1.5 \ M \ H_3PO_4$ (in $.5$)?