MolSynapsequestion bank

MolSynapse / Question bank / Periodic Table and Periodicity / Ionisation enthalpy

JEE Main levelSingle correct optionDifficulty 2 of 3pt122

Using the typical first ionisation enthalpies ( $Na$ 496, $Mg$ 738, $Al$ 577, $Si$ 787 in $kJ mo l^{- 1}$ ), the correct increasing order is

A $Na < Al < Mg < Si$
B $Al < Na < Mg < Si$
C $Na < Mg < Al < Si$
D $Na < Al < Si < Mg$

Answer: A

Arranging the given numbers: 496 (Na) < 577 (Al) < 738 (Mg) < 787 (Si). Al falls below Mg because its outer electron is a

3 p

electron, which is higher in energy than the

3 s

electron of Mg.

Practice Periodic Table and Periodicity More on Ionisation enthalpy

Previous questionNext question

More questions on Ionisation enthalpy