$19 \ g$ of a mixture containing $NaHCO_3$ and $Na_2CO_3$ on complete heating liberated $1.12 \ L$ of $CO_2$ at $STP$. The weight of the remaining solid was $15.9 \ g$. What is the weight (in $g$) of $Na_2CO_3$ in the mixture before heating?

$A$ sample of $NaNO_3$ weighing $0.38 \ g$ is placed in a $50.0 \ mL$ volumetric flask. The flask is filled to the mark with water. What is the molarity of the solution?

$5 \ g$ of $NaOH$ was dissolved in deionized water to prepare a $450 \ mL$ stock solution. What volume (in $mL$) of this solution would be required to prepare $500 \ mL$ of $0.1 \ M$ solution?
Given: Molar Mass of $Na$,$O$,and $H$ is $23$,$16$,and $1 \ g \ mol^{-1}$ respectively.

Six volumes of oxygen,on complete ozonisation,form ...... volumes of ozone.

What is the value of $w$ (mass of solute in grams) required to prepare a definite volume of a standard solution of known normality $(N)$?
[$N = \text{normality}$,$E = \text{equivalent weight}$,$V = \text{volume of solution in } mL$]

Calculate the volume of $CO_2$ at $NTP$ that can be obtained by heating $200 \ g$ of $80 \%$ pure $CaCO_{3(s)}$.