The number of moles of a solute in its solution is $20$ and the total number of moles is $80$. The mole fraction of the solute is:

The density of a stock solution of $29.2\% \, (w/w) \, HCl$ is $1.25 \, g \, mL^{-1}$. If the molar mass of $HCl$ is $36.5 \, g \, mol^{-1}$,what volume (in $mL$) of the stock solution is required to prepare $200 \, mL$ of $0.4 \, M \, HCl$ solution?

What volume of water in $mL$ is required to prepare a $0.20\,N$ solution from $1600\,mL$ of a $0.2050\,N$ solution?

What is the molarity of a $1 \ L$ solution of $93\% \ (w/v)$ $H_2SO_4$ (in $M$)? The density of the solution is $1.84 \ g/mL$.

Find out the molality of a solution prepared by dissolving $2.89 \ g$ of $NaCl$ in $0.159 \ L$ of water. The density of water is $1.00 \ g / mL$. (in $m$)

$200 \, mL$ of $0.6 \, N$ $H_2SO_4$ and $100 \, mL$ of $0.3 \, N$ $HCl$ are mixed together. The acidic normality of the resultant solution is $........ N$.