Question

The first ionisation potential of Na, Mg, Al and Si are in the

• A. Na < Mg >Al < Si
• B. Na > Mg > A1 > Si
• C. Na < Mg < Al > Si
• D. Na > Mg > Al < Si

Answer 1

Answer: (A)

Na < Mg >Al < Si

Answer 2

Ionisation energy increases from left to right in a period. However, exception occur between group 2 and group 13 elements on account of stability of electronic configuration of valence shell. $\Rightarrow$ The desired order is Na < Mg > A1 < Si