Between `Na^(+)` and `Ag^(+)` which is stronger Lewis acid and why?

Explanation

` Ag^+` ion is stronger Lewis acid than `Na^+. Ag^+` has 18-electron shell configuration (known as pseudo inert gas configuration) and causes greater polarisation than `Na^+` ion with 8-electron shell configuration. This is due to the fact that in case of 18-electrons shell ion there are 10 d-electrons in addition to 8s and p-electrons. The d-electrons donot shield the nuclear charge effectively and therefore, they have increased effective nuclear charge. Hence they cause greater polarisation and therefore, `Ag^+` is a stronger Lewis acid than `Na^+` ion.