The mole fraction of water in a $20\%$ aqueous solution of $H_2O_2$ is:

The molarity of the solution prepared by dissolving $6.3 \ g$ of oxalic acid $(H_{2}C_{2}O_{4} \cdot 2H_{2}O)$ in $250 \ mL$ of water in $mol \ L^{-1}$ is $x \times 10^{-2}$. The value of $x$ is ..... . (Nearest integer)
[Atomic mass : $H: 1.0, C: 12.0, O: 16.0]$

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

$A$ mixture of camphor in air is an example of which type of solution?

$A$ 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 $g$?

$250 \ g$ solution of $D$-glucose in water contains $10.8 \ \%$ of carbon by weight. The molality of the solution is nearest to (Given: Atomic weights are $H = 1 \ u, C = 12 \ u, O = 16 \ u$)