Choose the correct type of chemical reactions (Combination reaction/ decomposition reaction/ displacement reaction).

${\mathrm{PCl}}_5\underset{\mathrm{Cool}}{ \stackrel{∆}{\rightleftharpoons }} {\mathrm{PCl}}_3 + {\mathrm{Cl}}_2$

Choose the correct type of chemical reactions (Combination reaction/ decomposition reaction/ displacement reaction).

$\mathrm{Zn} + {\mathrm{H}}_2{\mathrm{SO}}_4 \to {\mathrm{ZnSO}}_4 +{\mathrm{H}}_2$

Choose the correct type of chemical reactions (Combination reaction/ decomposition reaction/ neutralisation reaction).

$\mathrm{NaOH} + \mathrm{HCl} \to \mathrm{NaCl} + {\mathrm{H}}_2\mathrm{O}$

Choose the correct type of chemical reaction.

$\mathrm{Pb}({\mathrm{NO}}_3{)}_2 + 2\mathrm{HCl} \to {\mathrm{PbCl}}_2 + 2{\mathrm{HNO}}_3$

Choose the correct type of chemical reaction.

$2\mathrm{KI} + {\mathrm{Cl}}_2 \to 2\mathrm{KCl} +{\mathrm{I}}_2$

State whether the following is reduction or oxidation.

${\mathrm{Fe}}^{2+} \to \mathrm{Fe}$

State whether the following is oxidation or reduction.

${\mathrm{Fe}}^{3+} \to {\mathrm{Fe}}^{2+}$

State whether the following reaction is oxidation or reduction.

${\mathrm{O}}^{2-}\stackrel{ }{\to }\mathrm{O}$.

State whether the following reaction is oxidation or reduction.

${\mathrm{Cr}}^{7+} \to {\mathrm{Cr}}^{5+}$