Compute the number of ions present in $5.85 \, g$ of sodium chloride.

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

How did Berzelius assign symbols to the elements?

$A$ sample of ethane $(C_2H_6)$ gas has the same mass as $1.5 \times 10^{20}$ molecules of methane $(CH_4)$. How many $C_2H_6$ molecules does the sample of gas contain?

State whether the following statement is true or false:
The chemical formulae of cupric oxide and cuprous oxide are $CuO$ and $Cu_{2}O$ respectively.

One mole of $H_{2}O$ means:
$(i)$ $18 \text{ g}$ of $H_{2}O$
$(ii)$ $6.022 \times 10^{23}$ molecules of $H_{2}O$
$(iii)$ $180 \text{ g}$ of $H_{2}O$
$(iv)$ $1.8 \text{ g}$ of $H_{2}O$