Explain why carbon can reduce copper oxide to copper but not calcium oxide to calcium.

Explanation

Carbon is a strong reducing agent. Hence, it can reduce copper oxide to copper as follows :
`CuO_((s)) + C_((s)) to Cu_((s)) + CO_((g))uparrow`
Calcium is much more reactive than copper. IT has greater affinity for oxygen than for carbon. Moreover, at high temperature, calcium formed, if any, combines with carbon to form calcium carbide.