Blue vitriol is

What is the composition of the white enamel of our teeth?

$10 \ mL$ of $2 \ M$ $NaOH$ solution is added to $20 \ mL$ of $1 \ M$ $HCl$ solution kept in a beaker. Now,$10 \ mL$ of this mixture is poured into a volumetric flask of $100 \ mL$ containing $2 \ moles$ of $HCl$ and made the volume up to the mark with distilled water. The solution in this flask is $:$

$3.0$ molal $NaOH$ solution has a density of $1.110 \, g/mL$. The molarity of the solution is

If one liter of air is repeatedly passed over heated copper and magnesium until no further reduction in volume occurs,the final volume of the air will be approximately ......... $mL$.

Which of the following has the minimum number of oxygen atoms?