Calculate the number of moles in $60 \text{ g}$ of carbon. (in $\text{ moles}$)

State three rules for writing the chemical formulae.

Give the formulae of the compounds formed from the following sets of elements:
$(a)$ Calcium and fluorine
$(b)$ Hydrogen and sulphur
$(c)$ Nitrogen and hydrogen
$(d)$ Carbon and chlorine
$(e)$ Sodium and oxygen
$(f)$ Carbon and oxygen

Express each of the following in kilograms:
$(a)$ $5.84 \times 10^{-3} \,mg$
$(b)$ $58.34 \,g$
$(c)$ $0.584 \,g$
$(d)$ $5.873 \times 10^{-21} \,g$

The chemical symbol for sodium is

Which of the following postulates of Dalton's atomic theory is challenged by the next generation of scientists?