QUESTIONS

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Give an example of a double displacement reaction?

Identify the substances that are oxidized and the substances that are reduced in the following reaction:
$4\mathrm{N}\mathrm{a}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{N}\mathrm{a}}_2\mathrm{O}\left(\mathrm{s}\right)$

Identify the substances that are oxidized and the substances that are reduced in the following reaction:
$\mathrm{C}\mathrm{u}\mathrm{O}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\to \mathrm{C}\mathrm{u}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$