Start learning →

JEE Main Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry — practice questions

Explore 3 free Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry questions in JEE Main Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

Practise Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry with Quill →

Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry questions and exercises with answers

Showing questions 1–3 of 3.

Among HF, HCl, HBr, HI: order of bond ENTHALPY (strength):Read the answer and worked solution →Effective nuclear charge (Z_eff) felt by an electron in 2p orbital of nitrogen, given Z = 7, screening constant σ ≈ 3.25:Read the answer and worked solution →Among NaCl, NaBr, NaI: order of melting points:Read the answer and worked solution →

Worked practice questions

Among HF, HCl, HBr, HI: order of bond ENTHALPY (strength):

  1. All equal
  2. HF > HCl > HBr > HI
  3. HCl > HF > HBr > HI
  4. HI > HBr > HCl > HF
Show answer and solution

Correct answer: B. HF > HCl > HBr > HI

As we go down the halogen group, bond length increases (atom size grows), so bond becomes WEAKER. So HF (shortest, strongest) > HCl > HBr > HI (longest, weakest). This is also why HI is the strongest acid in water (easiest to dissociate).

Open this question →

Effective nuclear charge (Z_eff) felt by an electron in 2p orbital of nitrogen, given Z = 7, screening constant σ ≈ 3.25:

  1. ~7
  2. ~1.85
  3. ~3.75
  4. ~5.75
Show answer and solution

Correct answer: C. ~3.75

Z_eff = Z - σ = 7 - 3.25 ≈ 3.75. Slater's rules give the approximate effective charge after accounting for shielding by inner electrons.

Open this question →

Among NaCl, NaBr, NaI: order of melting points:

  1. NaI > NaBr > NaCl
  2. NaCl > NaBr > NaI (smaller anion = stronger lattice)
  3. All equal
  4. NaBr > NaCl > NaI
Show answer and solution

Correct answer: B. NaCl > NaBr > NaI (smaller anion = stronger lattice)

As anion size grows (Cl⁻ < Br⁻ < I⁻), inter-ionic distance r grows, lattice energy ∝ 1/r decreases. **Hence melting point decreases:** NaCl (801°C) > NaBr (747°C) > NaI (661°C).

Open this question →

How to practise

  1. Choose a Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

Put it into practice

Continue with Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry practice for JEE Main. Read explanations as you go. No signup form needed to start.

Practise Unit 2A: Chemical Bonding, Lewis Diagrams & Molecular Geometry →

More Chemistry topics

Aldehydes, Ketones and Carboxylic AcidsElectrochemistryStructure of AtomThe d- and f-Block Elements & Coordination CompoundsSolutionsRedox ReactionsUnit 2B1: Transition Metals & Coordination CompoundsChemical Kinetics