$Elodea$ 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 $STP$.

The decomposition of $CaCO_3$ produces $11.2 \, dm^3$ of $CO_2$ gas at $STP$. What mass of $KOH$ in grams is required to completely neutralize this gas?

For the combustion reaction of $1 \, mol$ of a hydrocarbon $C_xH_y$,the coefficients of $O_2$,$CO_2$,and $H_2O$ involved are respectively:

Number of moles of oxygen gas evolved by electrolysis of $180 \ g$ of water?

$A$ $6 \ L$ sample of hard water has a total hardness of $200 \ ppm$ of $Mg^{2+}$ in the form of bicarbonates and chlorides. This sample is treated with $Na_2CO_3$ to eliminate all temporary hardness,and the new hardness is found to be $\frac{1000}{3} \ ppm$ of $CaCO_3$. Find the mass of $MgCl_2$ in the $6 \ L$ sample in $mg$. $(d_{H_2O} = 1 \ g/mL)$

$A$ mixture of $CaCl_{2}$ and $NaCl$ weighing $4.44 \ g$ is treated with sodium carbonate solution to precipitate all the $Ca^{2+}$ ions as calcium carbonate. The calcium carbonate so obtained is heated strongly to get $0.56 \ g$ of $CaO$. The percentage of $NaCl$ in the mixture (atomic mass of $Ca=40$) is