Calculate the volume of $99 \text{ g}$ of $CO_2$ at $STP$. (in $\text{ L}$)

When ${CO_2}_{(g)}$ is passed over hot coke,it is reduced to ${CO}_{(g)}$. When $0.5 \, L$ of ${CO_2}_{(g)}$ is passed over hot coke,the total volume of the gas increases by $700 \, mL$ at $STP$. The composition of the resulting gaseous mixture is:

Calculate percentage atom economy when $46 \ g$ ethanol is obtained from $64.5 \ g$ chloroethane and $56 \ g$ $KOH_{(aq)}$. (in $\%$)

$1 \ mol$ of metal '$M$' reacts completely with alcohol to give $1.5 \ mol$ of $H_2$. What is the valency of metal '$M$'?

Reaction of $x \ g$ of $Sn$ with $HCl$ quantitatively produced a salt. The entire amount of the salt reacted with $y \ g$ of nitrobenzene in the presence of the required amount of $HCl$ to produce $1.29 \ g$ of an organic salt (anilinium chloride) quantitatively.
$(1)$ The value of $x$ is. . . . .
$(2)$ The value of $y$ is. . . . .

The volume of $0.1 \ M \ HCl$ required in $mL$ to neutralise $20 \ mL$ of a solution containing $0.106 \ g$ of $Na_2CO_3$ is