The formula weight of $H_2SO_4$ is $98$. The weight of the acid in $400 \ mL$ of $0.1 \ M$ solution is ........... $g$.

What is the molality of a solution containing $300 \ mg$ of urea (molar mass $60 \ g/mol$) dissolved in $30 \ g$ of water (in $m$)?

$A$ solution is prepared by adding $2 \ g$ of $X$ to $1 \ mole$ of water. Mass percent of $X$ in the solution is $............. \ \%$

Concentrated $HCl$ is $10 \,N$. How can $1000 \,cc$ of $1 \,N \,HCl$ be prepared by dilution?

$3.0\, g$ of oxalic acid $[(CO_2H)_2 \cdot 2H_2O]$ is dissolved in a solvent to prepare a $250\, mL$ solution. The density of the solution is $1.9\, g/mL$. The molality and normality of the solution,respectively,are closest to

$0.1 \ mol$ of $NaCl$ is dissolved in $100 \ g$ of water. The mole fraction of $NaCl$ is