Classification of Elements
Assertion Na+ and Al3+ are isoelectronic but the magnitude of ionic radius of Al3+ is less than that of Na+.
Reason The magnitude of effective nuclear charge of the outer shell electrons in Al3+ is greater than that in Na+.
Which of the following represents the correct order of increasing first ionization enthalpy for Ca, Ba, S, Se and Ar ?
Assertion F2 has high reactivity.
Reason F — F bond has low bond dissociation enthalpy.
Assertion : The first ionisation enthalpy of Be is greater than that of B.
Reason : 2p-orbtial is lower in energy than 2s-orbital.