question_answer

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

A) \[Na<Mg>Al<Si\]            

B) \[Na>Mg>Al>Si\]

C) \[Na<Mg<Al>Si\]            

D) \[Na>Mg>Al<Si\]

Correct Answer: A

Solution :

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 : \[Na<Mg>Al<Sl\]