Mole fraction of solute in its $2$ molal aqueous solution is

The concentration of $1 \ L$ of $CaCO_3$ solution is $1000 \ ppm$. What is its concentration in $mol \ L^{-1}$ ?
$(Ca=40 \ u, O=16 \ u, C=12 \ u)$

Commercially available $H_2SO_4$ is $98 \ g$ by weight of $H_2SO_4$ and $2 \ g$ by weight of water. Its density is $1.38 \ g \ cm^{-3}$. Calculate the molality $(m)$ of $H_2SO_4$ (molar mass of $H_2SO_4$ is $98 \ g \ mol^{-1}$). (in $m$)

Which of the following solutions has the highest amount of solute (in grams)?

Explain $\% \ V/V$ in brief.

$25 \ g$ of a solute of molar mass $250 \ g \ mol^{-1}$ is dissolved in $100 \ mL$ of water to obtain a solution whose density is $1.25 \ g \ mL^{-1}$. The molarity and molality of the solution are respectively