Haemoglobin contains $0.33\%$ of iron by weight. The molecular weight of haemoglobin is approximately $67200$. The number of iron atoms (At. wt. of $Fe = 56$) present in one molecule of haemoglobin is

For what ratio of volumes should $0.4 \, M \ HCl$ and $0.9 \, M \ HCl$ be mixed to obtain a solution of $0.7 \, M \ HCl$?

The volume (in $mL$) of $0.1\, N$ $NaOH$ required to neutralize $10\, mL$ of $0.1\, N$ phosphinic acid is........

$A$ flask is weighed when filled with methane $(CH_4)$. The methane is then removed,and the flask is weighed again. When the flask is filled with oxygen $(O_2)$ at the same temperature and pressure,the mass of oxygen will be:

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 $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)

Match the following List-$I$ and List-$II$ at $STP$:

List-$I$	List-$II$
$A. 10 \ g \ CaCO_3 \xrightarrow{\Delta} \text{decomposition}$	$1. 0.224 \ L \ CO_2$
$B. 1.06 \ g \ Na_2CO_3 \xrightarrow{\text{Excess } HCl} \text{reaction}$	$2. 4.48 \ L \ CO_2$
$C. 2.4 \ g \ C \xrightarrow{\text{Excess } O_2} \text{combustion}$	$3. 0.448 \ L \ CO_2$
$D. 0.56 \ g \ CO \xrightarrow{\text{Excess } O_2} \text{combustion}$	$4. 2.24 \ L \ CO_2$
	$5. 22.4 \ L \ CO_2$