$1000 \ g$ aqueous solution of $CaCO_3$ contains $10 \ g$ of carbonate. Concentration of the solution is .......... $ppm$.

What is the mole fraction of the solute in a $1 \, m$ (molal) aqueous solution?

What is the mole fraction of the solute in a $2.5 \, m$ aqueous solution?

What is meant by the concentration of a solution?

$A$ solution is prepared by adding $2 \ g$ of a substance $A$ to $18 \ g$ of water. Calculate the mass per cent of the solute. (in $\%$)

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: At $10^{\circ} C$,the density of a $5 \ M$ solution of $KCl$ is given. The solution is cooled to $-21^{\circ} C$. The molality of the solution will remain unchanged.
Reason $R$: The molality of a solution does not change with temperature as mass remains unaffected by temperature.
In the light of the above statements,choose the correct answer from the options given below: