The mass of one atom of oxygen is:

Which of the following would weigh the highest?

$(a)$ Calculate the percentage of oxygen in $H_{2}O_{2}$.
$(b)$ Calculate the number of moles in $56 \, g$ of nitrogen gas $(N_{2})$.
$(c)$ Calculate the mass of $0.50$ moles of $Ca$ atoms.
$(d)$ Find out the number of particles in:
$(i)$ $5$ moles of methane gas $(CH_{4})$
$(ii)$ $92 \, g$ of sodium $(Na)$
(Atomic masses: $H=1, O=16, N=14, Ca=40, Na=23$)

What is a molecular formula? State with an example what information can be derived from a molecular formula.

Define mole. Give its symbol. What is the advantage of this mole concept?

Which of the following statements is not true about an atom?