Question

The electronic configuration of metal 'A' is 2,8,1 and that of metal 'B' is 2,8,2 . Which of the two metals is more reactive? Write their reaction with dilute hydrochloric acid.

Answer 1

the one with just 1 electron in its outer most shell is more reactive since it is more likely to lose or give away 1 electron and achieve a stable state of 2,8. based on the configuration the metal A is sodium, Na. metal B is magnesium Mg.
reactions being, A + HCl = ACl
B + 2HCl = BCl2 + H2

Answer 2

'A': 2,8,1 i.e. Na
'B': 2,8,2i.e.Mg
betweeen these Na is more reactive

rxñ ::
Na+HCl(dil.) -> NaCl+ H
Mg+HCl(dil.)-> MgCl+H
hope this helps