If the density of some lake water is $1.25\, g\, mL^{-1}$ and contains $92\, g$ of $Na^{+}$ ions per $kg$ of water,calculate the molality of $Na^{+}$ ions in the lake. (in $, m$)

If $5.0 \ g$ of $BaCl_2$ is present in $10^6 \ g$ solution,the concentration is .......... $ppm$.

At $T \ (K)$,$100 \ g$ of $98\%$ $H_2SO_4$ $(w/w)$ aqueous solution is mixed with $100 \ g$ of $49\%$ $H_2SO_4$ $(w/w)$ aqueous solution. What is the mole fraction of $H_2SO_4$ in the resultant solution?
(Given: Atomic mass $H = 1 \ u; S = 32 \ u; O = 16 \ u$)
(Assume that temperature after mixing remains constant)

What is the mass ratio of ethylene glycol $(C_2H_6O_2, \text{molar mass} = 62 g/mol)$ required for making $500 g$ of $0.25 m$ aqueous solution and $250 mL$ of $0.25 M$ aqueous solution?

Dissolving $120 \ g$ of a compound (mol. wt $= 60$) in $1000 \ g$ of water gave a solution of density $1.12 \ g \ mL^{-1}$. The molarity of the solution is: (in $M$)

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