Question

The first ionisation enthalpies 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

Answer 1

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

order Na < Al < Mg < Si

- the first ionisation enthalpies are

Na = 496 kJ/mol

Mg = 737 kJ/mol

Al = 577 kJ/mol

Si = 786 kJ/mol

- the order can be given as Na< Mg > Al <Si

-So the correct option is (a)