PrepRung
Sign inSign up free

JEE Main 2023 · Chemistry · Periodic Properties · easy

The correct increasing order of first ionisation enthalpy is

Single correct option

The correct increasing order of first ionisation enthalpy is
  1. A. Na<Al<Mg<Si\mathrm{Na<Al<Mg<Si}
  2. B. Na<Mg<Al<Si\mathrm{Na<Mg<Al<Si}
  3. C. Al<Na<Mg<Si\mathrm{Al<Na<Mg<Si}
  4. D. Na<Al<Si<Mg\mathrm{Na<Al<Si<Mg}
Show answer and solution

Answer: (A) Na<Al<Mg<Si\mathrm{Na<Al<Mg<Si}

Across period 3 the general trend is increasing, with two dips: Al is lower than Mg because its outer electron is in the higher-energy, well-shielded 3p3p orbital while Mg has a stable filled 3s23s^2. Values (kJ/mol): Na 496496, Al 577577, Mg 738738, Si 786786. So Na<Al<Mg<Si\mathrm{Na<Al<Mg<Si}.
Report a mistake

Original question written in the JEE Main 2023 pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake