The numbers 17.0145 and 21.0235 were rounded to three figures after the decimal point. The resulting numbers, respectively, are

The amount of carbon dioxide evolved upon complete combustion of $116 g$ of $n$-butane is

(Given: atomic mass in amu $\mathrm{H}=1, \mathrm{C}=12$ and $\mathrm{O}=16$ )

The number of hydrogen atoms present in 5.4 g of urea is:

(Given: Molar mass of urea : $60 \mathrm{~g} \mathrm{~mol}^{-1}$

$\mathrm{N}_{\mathrm{A}}: 6.022 \times 10^{23}$ particles $\mathrm{mol}^{-1}$ )

When $1 \mathrm{dm}^3$ of CO₂ gas is passed over hot coke the volume of gaseous mixture after complete reaction at STP becomes $1.4 \mathrm{dm}^3$. The composition of the gaseous mixture at STP is :