PYQSide ExamsMy practice

Classification of Elements and Periodicity in Properties · Question 17

JEE Main 2026 (Online) 22nd January Morning ShiftMCQMedium📈 Topic in 42% papers+4−1
1

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

Answer

(1) 1402

Solution

Alkaline K2HgI4 is Nessler's reagent; it gives a brown precipitate of basic mercury(II) amido-iodine with ammonia.

EH3 = NH3 and the cation (EHx)+ = NH4+ E = N (first element of group 15).

First ionisation enthalpies ( kJ mol-1): B 801, C 1086, N 1402, O 1314 (≈ 1312).

N has the stable half-filled 2p3 configuration its ionisation enthalpy is even higher than that of O.

For E (nitrogen), iH1 = 1402 kJ mol-1

Answer: (1)

JEE Main 2026 (Online) 22nd January Morning Shift

Keep practising — Classification of Elements and Periodicity in Properties

2

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
JEE Main 2026 (Online) 22nd January Evening Shift
3

Which of the following represents the correct trend for the mentioned property? Choose the correct answer from the options given below :

  1. B and C only
  2. A, B and D only
  3. A and B only
  4. A, B, C and D
JEE Main 2026 (Online) 21st January Morning Shift
4

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. Both Statement I and Statement II are true
  3. Statement I is false but Statement II is true
  4. Both Statement I and Statement II are false
JEE Main 2026 (Online) 21st January Evening Shift
5

The atomic number of the element from the following with lowest 1st ionisation enthalpy is :

  1. 32
  2. 35
  3. 19
  4. 87
JEE Main 2025 (Online) 8th April Evening Shift
6

Choose the incorrect trend in the atomic radii (r) of the elements.

  1. rRb < rCs
  2. rAt < rCs
  3. rBr < rK
  4. rMg < rAl
JEE Main 2025 (Online) 7th April Evening Shift
7

Which of the following statements are correct? Choose the correct answer from the options given below:

  1. A, C and D Only
  2. B and C Only
  3. B and D Only
  4. B, C and E Only
JEE Main 2025 (Online) 3rd April Morning Shift
8

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

  1. A-IV, B-I, C-II, D-III
  2. A-IV, B-III, C-I, D-II
  3. A-III, B-I, C-IV, D-II
  4. A-II, B-III, C-IV, D-I
JEE Main 2025 (Online) 3rd April Evening Shift
9

Electronic configuration of four elements A, B, C and D are given below: (A) 1s2 2s2 2p3 (B) 1s2 2s2 2p4 (C) 1s2 2s2 2p5 (D) 1s2 2s2 2p2 Which of the following is the correct order of increasing electronegativity (Pauling's scale)?

  1. D < A < B < C
  2. A < B < C < D
  3. A < C < B < D
  4. A < D < B < C
JEE Main 2025 (Online) 2nd April Evening Shift
10

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

  1. Statement I is incorrect but Statement II is correct
  2. Both Statement I and Statement II are correct
  3. Statement I is correct but Statement II is incorrect
  4. Both Statement I and Statement II are incorrect
JEE Main 2025 (Online) 29th January Morning Shift
11

The incorrect decreasing order of atomic radii is

  1. Si > P > Cl > F
  2. Mg > Al > C > O
  3. Al > B > N > F
  4. Be > Mg > Al > Si
JEE Main 2025 (Online) 28th January Morning Shift

All Classification of Elements and Periodicity in Properties PYQs →

PDFDownload Classification of Elements and Periodicity in Properties PYQs as PDF Free, with answer key and a QR code to every solution — print it or study offline⬇
All JEE Main Chemistry chapters
Physical ChemistrySome Basic Concepts of ChemistryStructure of AtomStates of MatterThermodynamicsEquilibriumRedox ReactionsSolutionsElectrochemistryChemical Kinetics
Inorganic ChemistryClassification of Elements and Periodicity in PropertiesChemical Bonding and Molecular Structurep-Block Elements (Group 13 & 14)p-Block Elements (Group 15–18)d- and f-Block ElementsCoordination Compounds
Organic ChemistryOrganic Chemistry – Some Basic Principles and TechniquesIsomerismHydrocarbonsHaloalkanes and HaloarenesAlcohols, Phenols and EthersAldehydes, Ketones and Carboxylic AcidsAminesBiomoleculesPrinciples Related to Practical Chemistry