A 20 L vessel contains 0.1 mole of $O_2$ at 300 K. $O_3$ is prepared in the vessel by subjecting $O_2$ to silent electric discharge till the volume is reduced to 15 L at 300K. What is the number of moles of $O_3$ formed?

The number of moles in 11.2 L at STP of oxygen

If Avogadro's number were $6.022 imes 10^{15} \, mol^{-1}$, what would be the mass of one mole of water (H$_2$O)? (Atomic masses: H = 1 u, O = 16 u)

$3.011\,\,x\,\,{10^{^{23}}}$ atoms of an element weights 1.15 g. The atomic mass of the element is

One mole of $\;{\rm{C}}{{\rm{O}}_2}$ contains:

Equal masses of oxygen and ozone are present in a container at 298 K. The ratio of their partial pressures ($P_{O_2} : P_{O_3}$) is:

Upon heating, 15.0 g of impure zinc carbonate decomposes completely to produce zinc oxide and carbon dioxide. If 5.6 g of zinc oxide is formed, calculate the percentage purity of the zinc carbonate sample. (Atomic weight: $Zn = 65.4$)

Which of these samples contains the fewest atoms?

A gaseous mixture contains oxygen and nitrogen in the ratio of $1:4$ by weight. Therefore, the ratio of their number of molecules is:

The oxidation number and covalency of sulphur in the sulphur molecule $\left( {{S_8}} \right)$ are respectively :

A student heats 40.0 g of a mixture containing magnesium carbonate and some inert impurities. Upon complete decomposition, 8.0 g of magnesium oxide is formed. Calculate the percentage by mass of magnesium carbonate in the original mixture. (Atomic weight: $Mg = 24$)