(a) "Displacement reactions also play a key role in extracting metals in the middle of the reactivity series." Justify this statement with two examples. (b) Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon?

(a) Displacement reactions play a key role in extracting metals in the middle of the reactivity series because these metals cannot be obtained by reduction of their oxides by carbon. For example, iron and zinc can be obtained by reducing their oxides with carbon. However, metals like copper and mercury are obtained by reducing their oxides with hydrogen or carbon monoxide. (b) Metals high up in the reactivity series cannot be obtained by reduction of their oxides by carbon because they have a greater affinity for oxygen than carbon. As a result, carbon cannot displace these metals from their oxides.