Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in $grams$) of the salt required to achieve $10 \; ppm$ of iron in $100 \; kg$ of wheat is
Atomic weight : $Fe = 55.85$,$S = 32.0$,$O = 16.00$

Calculate the mass in $kg$ of $4.48 \ dm^3$ of carbon dioxide $(CO_2)$ at $STP$.

Calculate the approximate mass (in $g$) of $H_2S$ required for the following reaction when $15 \ L$ of oxygen at $STP$ reacts completely.
$2 H_2S_{(g)} + 3 O_{2(g)} \longrightarrow 2 SO_{2(g)} + 2 H_2O_{(g)}$
(molar mass of $H_2S = 34 \ g \ mol^{-1}$)

The volume occupied by $4.4 \ g$ of $CO_2$ at $STP$ is ............... $L$.

$A$ hydrocarbon containing $C$ and $H$ has $92.3 \% C$. When $39 \ g$ of hydrocarbon was completely burnt in $O_2$,$x$ moles of water and $y$ moles of $CO_2$ were formed. $x$ moles of water is sufficient to liberate $0.75$ moles of $H_2$ with $Na$ metal. What is the weight (in $g$) of oxygen consumed? $(C=12 \ u; H=1 \ u)$

$20 \ mL$ of $0.2 \ M \ Al_2(SO_4)_3$ is mixed with $20 \ mL$ of $6.6 \ M \ BaCl_2$. The concentration of $Cl^{-}$ ion in the final solution is $......... \ M$.