What is meant by selectivity of a catalyst ? Explain giving examples.

Explanation

The selectivity of a catalyst is its ability to direct a reaction to yield a particular product. For example, starting with `H_2` and CO and using different catalysts, we get different products.
(i) `CO(g) + 3H_2(g) overset(Ni)to CH_4(g) + H_2O (g)`
(ii) `CO(g) + 2H_2 (g) overset(Cu//ZnO-Cr_2O_3)to CH_3OH(g)`
(iii) `CO(g) + H_2 overset(Cu)to HCHO (g)`