The amount of metallic $Zn$ (atomic weight $= 65.4$) required to react with aqueous sodium hydroxide to produce $1 \ g$ of $H_2$ is $.... \ g$.

Concentrated aqueous sulphuric acid is $98\% \ H_2SO_4$ by mass and has a density of $1.80 \ g \ mL^{-1}$. The volume of acid required to make $1 \ L$ of $0.1 \ M \ H_2SO_4$ solution is ........ $mL$.

How many moles of $KCl$ are dissolved in $1000 \ mL$ of $3 \ M$ $KCl$ solution?

What is the volume in $dm^3$ occupied by $3 \ mol$ of ammonia gas at $STP$?

The normality of $0.3 \ M$ phosphorous acid $(H_3PO_3)$ is

$A$ $6 \ L$ 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 $mg$. $(d_{H_2O} = 1 \ g/mL)$