The chemical symbol for sodium is

Interpret the number of moles of oxygen atoms in $PO_{4}^{3-}$ ion.

$(a)$ Calculate the number of moles in $112 \, g$ of iron.
$(b)$ Calculate the mass of $0.5$ mole of sugar $(C_{12}H_{22}O_{11})$.
$(c)$ Calculate the number of atoms in $8 \, g$ of oxygen $(O_2)$ molecules.
(Atomic mass of $Fe = 56 \, u, C = 12 \, u, H = 1 \, u, O = 16 \, u, N_A = 6.022 \times 10^{23} \, mol^{-1}$)

State the postulate of Dalton's atomic theory which led to the law of conservation of mass. Calculate the molecular mass of water.

Write the chemical formulae for the following substances and calculate the molecular mass for each one of them:
$(a)$ Caustic potash
$(b)$ Baking soda
$(c)$ Limestone
$(d)$ Caustic soda
$(e)$ Ethanol
$(f)$ Common salt

Raunak took $5 \, mol$ of carbon atoms in a container and Krish also took $5 \, mol$ of sodium atoms in another container of the same weight. $(a)$ Whose container is heavier? $(b)$ Whose container has a greater number of atoms?