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Classification of Elements and Periodicity in Properties

JEE Main 2026 (Online) 4th April Evening ShiftMCQEasy📈 Topic in 32% papers+4−1
Ques. 1JEE Main 2026, 4 April (Evening Shift)

The 1st ionization enthalpy for Mg is +737 kJ/mol. The most probable estimated value of the 2nd ionization enthalpy of Mg is .

  1. −906 kJ/mol
  2. −856 kJ/mol
  3. +1450 kJ/mol
  4. +590 kJ/mol

Answer

(3) +1450 kJ/mol

Solution

Energy is always absorbed to remove an electron ⇒ ionisation enthalpy is positive ⇒ (1) and (2) are ruled out.

The 2nd electron is removed from Mg+, a positive ion: the remaining electrons feel a larger effective nuclear charge

⇒ iH2 > iH1 (= 737 kJ/mol) ⇒ (4), +590 kJ/mol, is ruled out.

Mg+ ([Ne] 3s1) still loses a valence 3s electron, so iH2 is roughly double iH1 (actual value ≈ 1450 kJ/mol).

Answer: (3)

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Ques. 2JEE Main 2026, 2 April (Morning Shift)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
Ques. 3JEE Main 2026, 2 April (Evening Shift)

The correct set that contains all kinds (basic, acidic, amphoteric and neutral) of oxides is :

  1. Na2O, K2O, Al2O3 and As2O3
  2. Al2O3, As2O3, CO and NO
  3. K2O, Cl2O7, As2O3 and NO
  4. Na2O, N2O, Al2O3 and CO
Ques. 4JEE Main 2026, 2 April (Evening Shift)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Both Statement I and Statement II are true
  2. Both Statement I and Statement II are false
  3. Statement I is true but Statement II is false
  4. Statement I is false but Statement II is true
Ques. 5JEE Main 2026, 28 January (Morning Shift)

In period 4 of the periodic table, the elements with highest and lowest atomic radii are respectively.

  1. Rb & Br
  2. Na & Cl
  3. K & Br
  4. K & Se
Ques. 6JEE Main 2026, 28 January (Evening Shift)

Consider the elements N, P, O, S, Cl and F. The number of valence electrons present in the elements with most and least metallic character from the above list is respectively.

  1. 7 and 5
  2. 6 and 7
  3. 5 and 7
  4. 5 and 6
Ques. 7JEE Main 2026, 24 January (Morning Shift)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

  1. Both Statement I and Statement II are false
  2. Statement I is false but Statement II is true
  3. Statement I is true but Statement II is false
  4. Both Statement I and Statement II are true
Ques. 8JEE Main 2026, 24 January (Evening Shift)

The correct order of C, N, O and F in terms of second ionisation potential is

  1. C < N < F < O
  2. C < F < N < O
  3. F < N < C < O
  4. C < O < N < F
Ques. 9JEE Main 2026, 23 January (Morning Shift)

The correct trend in the first ionization enthalpies of the elements in the 3rd period of periodic table is :

  1. Si < S < Al < P < Cl
  2. Al < Si < S < P < Cl
  3. S < Si < Al < P < Cl
  4. Al < S < P < Si < Cl
Ques. 10JEE Main 2026, 23 January (Evening Shift)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

  1. Statement I is true but Statement II is false
  2. Statement I is false but Statement II is true
  3. Both Statement I and Statement II are true
  4. Both Statement I and Statement II are false
Ques. 11JEE Main 2026, 22 January (Morning Shift)

A 'p'-block element (E) and hydrogen form a binary cation (EHx)+, while EH3 on treatment with K2HgI4 in alkaline medium gives a precipitate of basic mercury(II) amido-iodine. Given below are first ionisation enthalpy values ( kJ mol-1) for first element each from group 13, 14, 15 and 16. Identify the correct first ionisation enthalpy value for element E.

  1. 1402
  2. 1086
  3. 801
  4. 1312

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