The number of chlorine atoms in $1.98 \ g$ of $BaCl_2$ is ..... (Atomic weight of $Ba = 137$,$Cl = 35.5$)

$Elodea$ is an aquatic plant that performs photosynthesis in water. The photosynthesis reaction is given by: $6CO_{2(g)} + 6H_2O_{(l)} \to C_6H_{12}O_{6(aq)} + 6O_{2(g)}$. Calculate the mass of $CO_2$ in $g$ required to produce $112 \, mL$ of oxygen at $STP$.

$5 \ g$ of $NaOH$ was dissolved in deionized water to prepare a $450 \ mL$ stock solution. What volume (in $mL$) of this solution would be required to prepare $500 \ mL$ of $0.1 \ M$ solution?
Given: Molar Mass of $Na$,$O$,and $H$ is $23$,$16$,and $1 \ g \ mol^{-1}$ respectively.

$1 \ g$ of a carbonate $(M_2CO_3)$ on treatment with excess $HCl$ produces $0.01 \ mol$ of $CO_2$. The molar mass of $M_2CO_3$ is $.......... \ g \ mol^{-1}$. (Nearest integer)

One mole of fluorine is reacted with two moles of hot concentrated $KOH$. The products formed are $KF, H_2O$ and $O_2$. The molar ratio of $KF, H_2O$ and $O_2$, respectively is

For per gram of reactant,the maximum quantity of $N_2$ gas is produced in which of the following thermal decomposition reactions? (Given: Atomic wt. : $Cr = 52 \ u, Ba = 137 \ u$).