If the density of $1 \ mol$ of a gas at $NTP$ is $0.1784 \ g/L$,what is the weight of $1 \ mol$ of the gas in $g$?

$100 \, mL$ of $Na_{3}PO_{4}$ solution contains $3.45 \, g$ of sodium. The molarity of the solution is $..... \times 10^{-2} \, mol \, L^{-1}$ $(Nearest \, integer)$.
[$Atomic \, Masses - Na: 23.0 \, u, O: 16.0 \, u, P: 31.0 \, u$]

How many litres of $CO_2$ at $STP$ will be formed when $100 \ mL$ of $0.1 \ M \ H_2SO_4$ reacts with excess of $Na_2CO_3$?

$A$ mixture of $CaCl_{2}$ and $NaCl$ weighing $4.44 \ g$ is treated with sodium carbonate solution to precipitate all the $Ca^{2+}$ ions as calcium carbonate. The calcium carbonate so obtained is heated strongly to get $0.56 \ g$ of $CaO$. The percentage of $NaCl$ in the mixture (atomic mass of $Ca=40$) is

$A$ person consumes $640 \, g$ of $O_2$ daily. If all the $O_2$ is used for the conversion of sugar into $CO_2$ and $H_2O$,how much sucrose $(C_{12}H_{22}O_{11})$ is consumed in the body per day and how much heat in $kJ$ is produced (in $.33$)? Given: $\Delta H_{combustion} \text{ of sucrose} = -5645 \, kJ \, mol^{-1}$.

Which of the following reactions exhibits good atom economy according to the principles of green chemistry?