Question

why non metals do no displace hydrogen from dilute acids

Answer 1

Generally non metals do not have tendency to lose an electron so the the electron to the hydrogen ion cannot be given by the non metals Hence non metals do not displace hydrogen from dilute acids

Answer 2

the reason why non-metals do not displace hydrogen from dilute acids is because unlike metals, non-metals do not have a tendency to lose electrons but to gain electrons. Metals have a tendency to lose electrons. These electrons, which are readily lost by reactive metals like sodium, potassium etc are accepted by hydrogen ions of the acids, reducing them to hydrogen gas (H2).

2 H+ + 2e- → H2

However, non-metals do not lose electrons readily, because of which they do not displace hydrogen from acids. Another important point to note is that not all metals will displace hydrogen from acids. Only those metals which are reactive than hydrogen will displace H2from acids.