Assertion: The greater the ionisation energy the greater the non-metallic character.
Reason: Metals are electron accepting and non-metals are electron donating.
The assertion is true but the reason is false.
Metals are electron donating and non-metals are electron accepting. Therefore, the reason was given to us which says "Metals are electron accepting and non-metals are electron donating" is false.
The reason why metals are electron donating is that they have low ionisation energy which means it does not require a lot of energy for them to lose electrons. Therefore, the greater the ionisation energy the lesser the metallic character and greater the non-metallic character. Thus, the assertion is true.
Hence, the assertion is true but the reason is false.