The number of moles of $NaOH$ in $2 \ L$ of $0.5 \ M \ NaOH$ solution is ..........

Explain the concept of reactions in solutions and mass percentage.

Explain molarity and molality in short.

$x \ g$ 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]

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

If $23 \ g$ of ethanol ($C_2H_5OH$,molar mass $= 46 \ g \ mol^{-1}$) is dissolved in $500 \ mL$ of solution,find the molarity of the solution in $M$.