Explain the following:
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.

Explanation

i.Metal A with electronic configuration of (2, 8, 1) is sodium (Na).
ii. Metal B with electronic configuration of (2, 8, 2) is magnesium (Mg).
iii. Metal A is more reactive than B as it has to lose only one electron from the outermost shell while metal B has to lose two electrons, to achieve a stable electronic configuration.
iv. Both sodium and magnesium react with dil. HCl to form corresponding salt and release hydrogen gas.
`underset"Sodium"(2Na_((s))) + underset"Hydrochloric acid"(2HCl_((aq))) to underset"Sodium chloride"(2NaCl_((aq))) + underset"Hydrogen"(H_2 uarr)`
`underset"Magnesium"(Mg_((s))) + underset"Hydrochloric acid"(2HCl_((aq))) to underset"Magnesium chloride"(MgCl_(2((aq)))) + underset"Hydrogen"(H_2 uarr)`