$A$ solution is prepared by adding $2 \ g$ of $X$ to $1 \ mole$ of water. Mass percent of $X$ in the solution is $............. \ \%$

$A$ $500 \ g$ toothpaste sample has $0.2 \ g$ fluoride concentration. What is the concentration of $F^-$ in terms of $ppm$ level?

$A$ solution of $x \ g$ of an optically active substance dissolved in $10 \ mL$ of alcohol is placed in a polarimeter tube of $10 \ cm$ length. The observed rotation is $+2^o$. If the specific rotation is $+16^o$,what is the value of $x$ in $g$?

The unit of mole fraction is:

By dissolving $0.35 \, \text{mole}$ of sodium chloride in water,$1.30 \, \text{L}$ of salt solution is obtained. The molarity of the resulting solution should be reported as $..... \, \text{M}$.

The molarity of the solution obtained by mixing $750 \ mL$ of $0.5 \ (N) \ HCl$ with $250 \ mL$ of $2 \ (M) \ HCl$ is ........... $M$.