What is the $SI$ prefix for each of the following multiples and submultiples of a unit?
$(a)$ $10^{3}$
$(b)$ $10^{-1}$
$(c)$ $10^{-2}$
$(d)$ $10^{-6}$
$(e)$ $10^{-9}$
$(f)$ $10^{-12}$

Which of the following compounds contain polyatomic ions?
$NaOH, NaCl, Na_{2}O, NaNO_{3}$

Name the international organization that approves the names of elements. Give an example with an explanation to show that the Law of Conservation of Mass applies to physical changes as well.

Which of the following correctly represents $360 \, g$ of water?
$(i)$ $2$ moles of $H_2O$
$(ii)$ $20$ moles of water
$(iii)$ $6.022 \times 10^{23}$ molecules of water
$(iv)$ $1.2044 \times 10^{25}$ molecules of water

Give one example each of:
$(a)$ Triatomic element
$(b)$ Monoatomic molecule
$(c)$ Polyatomic element
$(d)$ Polyatomic ion

$(a)$ What are molecules? Using examples, differentiate between the molecules of an element and a compound.
$(b)$ Derive the chemical formulae of the molecules formed between the following ions:
$(i)$ $Al^{3+}$ and $SO_{4}^{2-}$
$(ii)$ $Ba^{2+}$ and $NO_{3}^{-}$