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CBSE Practice: Chemistry Class 12

CBSE Class 12 Chemistry — Practice Problems

10 MCQ questions covering electrochemistry, chemical kinetics, solutions, p-block/d-block elements, and polymers from the NCERT syllabus. Select an option to check your answer and view the explanation.

Electrochemistry and Chemical Kinetics

Solutions and P-Block Elements

D-Block Elements and Polymers

Intuition

Chemistry is the science of substances and their transformations: From everyday reactions like cooking to industrial processes like steel-making, chemistry explains what things are made of and how they change. The mole concept connects atomic-scale reactions to laboratory-scale quantities.

Why it matters: Chemical understanding is essential for healthcare, environmental science, food technology, and material development.

The key insight: Balancing chemical equations is not just arithmetic, it reflects the physical law of conservation of mass that atoms are rearranged, not created or destroyed.

Common Mistakes

Confusing intermolecular and intramolecular forces: Hydrogen bonding, dipole-dipole interactions, and van der Waals forces are intermolecular (between molecules) and affect physical properties like boiling point. Covalent and ionic bonds are intramolecular (within molecules) and determine chemical identity. Mixing these up leads to incorrect predictions about boiling points and solubility.

Using the wrong value of the gas constant RR: The value of RR depends on the units used: 8.3148.314 J K−1^{-1} mol−1^{-1} for energy calculations, 0.08210.0821 L atm K−1^{-1} mol−1^{-1} for gas law problems with pressure in atm. Using 8.3148.314 when the problem uses litres and atmospheres gives wrong numerical answers.

Forgetting to balance redox equations before applying electrochemistry formulas: The Nernst equation and EMF calculations require balanced half-reactions with correct electron counts. Unbalanced equations give incorrect cell potentials and stoichiometric ratios. Always balance atoms first, then charges, before substituting into formulas.

Cross-References

  • Site Home: Main landing page for CBSE notes.
  • Chemistry: Chemistry notes covering organic and physical chemistry.
  • Physics: Physics notes covering mechanics and thermodynamics.
  • Practice: Practice problems for revision.

Detailed Content

Core Concepts

Worked Examples

Common Mistakes

  • Rushing through foundational material
  • Not practising problems after reading
  • Failing to connect concepts across topics

Further Reading

See also