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

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:

In a water sample,the concentration of $F^-$ ions is $10 \ ppm$ by weight-volume. What is the concentration of $F^-$ in $\% W/V$ in that solution?

The molality of $90\%$ ${H_2SO_4}$ solution is [density $= 1.8 \ g/mL$].

When $5 \ g$ of acetic acid is dissolved in $1 \ L$ of ethanol,assuming no reaction occurs between them,calculate the molality of the resulting solution. (Density of ethanol = $0.789 \ g/mL$) (in $m$)

What is the approximate normality of a $10\% (W/V)$ $H_2SO_4$ solution?