$A$ sample of drinking water is found to be severely contaminated with chloroform $(CHCl_3)$,which is a suspected carcinogen. If the level of contamination is $15 \ ppm$ (by mass),express this in percentage by mass.

The number of gram molecules of a substance present in unit volume is termed as

$x \ g$ of $NaCl$ is added to water in a beaker with a lid. The temperature of the system is raised from $1^{\circ}C$ to $25^{\circ}C$. Which out of the following plots is best suited for the change in the molarity $(M)$ of the solution with respect to temperature? [Consider the solubility of $NaCl$ remains unchanged over the temperature range]

Write the formula for percentage by weight.

Which of the following solutions has the highest normality?

The mole fraction of a solute in a binary solution is $0.1$. At $298 \ K$, molarity of this solution is same as its molality. Density of this solution at $298 \ K$ is $2.0 \ g \ cm^{-3}$. The ratio of molecular weights of the solute and the solvent $(M_{solute} / M_{solvent})$ is: