The size of `Al^(3+)` is lower than that of F. Justify,

Density of ice is lower than that of water.

Assertion: The ionic size of O^(2-) is bigger than that of F^(-) ion. Reason: The O^(2-) and F^(-) are isoelectronic ions.

Assertion: Na^(+) and Al^(3+) are isoelectronic but the magnitude of the ionic radius of Al^(3+) is less than that of Na^(+) Reason: The magnitude of effective nuclear charge of the outer shell electrons in Al^(3+) is greater than in Na^(+)

Justify the following: The electron gain enthalpy of 'F' is lower than that of 'Cl .

The electron affinity of nitrogen is lower than that of carbon because

The first ionization enthalpy of sodium is lower than that of magnesium but its second ionisation enthalpy is higher than that of magnesium. Explain.

Assertion : The 1^(st) IP of Be is greater than that of B Reason : 2p orbital is lower in energy than 2s