Write the formula of the compound formed - given symbols and combining power or capacity (valency) of each element in the compound.

${\mathrm{Ca}}^{2+} {{\mathrm{NO}}_3}^{1-}$

Match the formulas of the following gases with their correct names.

Gases - a) ${\mathrm{H}}_2$ b) ${\mathrm{N}}_2$ c) ${\mathrm{O}}_2$ d) ${\mathrm{Cl}}_2$ e) $\mathrm{HCl}$ f) ${\mathrm{NH}}_3$ g) $\mathrm{CO}$ h) ${\mathrm{CO}}_2$ i) ${\mathrm{SO}}_2$ j) $\mathrm{NO}$ k) ${\mathrm{NO}}_2$

Names - 1. Ammonia 2. Nitrogen dioxide 3. Oxygen 4. Hydrogen 5. Nitrogen 6. Chlorine 7. Carbon monoxide 8. Sulphur dioxide 9. Nitrogen monoxide 10. Carbon dioxide 11. Hydrogen chloride.

In the chemical word equation:

Zinc $+$ Sulphuric acid $\to$ Zinc sulphate $+$ Hydrogen

a) State the reactants and products of the above reaction. What does the arrow indicate?

b) The molecular equation is $\mathrm{Zn} + {\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{ZnSO}}_4 + {\mathrm{H}}_2\left[\mathrm{g}\right]$. State what [g] represents?

Match the compounds with their correct formulas.

Explain the term mixtures. Give an example of mixtures of 

a) two elements

b) two compounds

c) elements and compounds