When $22.4 \, L$ of $C_4H_8$ at $STP$ is burnt completely,$89.6 \, L$ of $CO_2$ gas at $STP$ and $72 \, g$ of water are produced. The volume of the oxygen gas at $STP$ consumed in the reaction is closest to $.... \, L$

$14 \ g$ of element $X$ combines with $16 \ g$ of oxygen. Based on this,which of the following statements is incorrect?

What volume of $CO_2$ at $STP$ is obtained by thermal decomposition of $20 \ g$ $KHCO_3$? [Atomic weight of $K = 39$]
$2KHCO_{3(s)} \to K_2CO_{3(s)} + CO_{2(g)} + H_2O_{(g)}$

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time,the passage of air is stopped,but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$) of $Pb$ produced per $kg$ of $O_2$ consumed is $. . . . .$ (Atomic weights in $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)

The most abundant elements by mass in the body of a healthy human adult are: Oxygen $(61.4\%);$ Carbon $(22.9\%),$ Hydrogen $(10.0\%);$ and Nitrogen $(2.6\%).$ The weight which a $75 \ kg$ person would gain if all $^1H$ atoms are replaced by $^2H$ atoms is ....... $kg$.

The number of millimoles and milliequivalents of $Ba(OH)_2$ in $0.2 \, L$ of $0.2 \, M \, Ba(OH)_2$ solution are respectively: