CBSE Class 12 Chemistry Exam 2025: Important Topics and Last-Minute Preparation Tips for Students

The Central Board of Secondary Education (CBSE) will conduct the Class 12 Chemistry Board Exam on February 27, 2025. The exam will be held in a single shift from 10:30 AM to 1:30 PM. With only some  time left for the exam, students must focus on revising important topics efficiently and managing their time wisely. Chemistry requires a deep understanding of concepts, memorisation of reactions, and problem-solving skills, making structured revision essential.

To help students prepare effectively, here are key topics from Organic, Inorganic, and Physical Chemistry, along with last-minute preparation strategies.

Key Topics in Organic Chemistry

Summarising Reactions

Compile all organic reactions chapter-wise into 4-5 pages or flowcharts for quick revision. Focus on name reactions such as:

• Aldol Condensation
• Cannizzaro Reaction
• Clemmensen Reduction
• Hoffmann Bromamide Degradation

Understand the role of reagents by categorising them:

• Oxidising Agents
• Reducing Agents

Practice conceptual questions using NCERT textbooks to strengthen understanding and use the correct terminology.

Distinguishing Tests

Learn how to differentiate between functional groups using tests, with reactions and observations rather than just naming the test. Some important ones include:

• Tollen’s Test and Fehling’s Test for aldehydes
• Lucas Test
• Iodoform Test
• Carbylamine Reaction
• Hinsberg Test

Key Topics in Physical Chemistry

Formula Compilation

Prepare a comprehensive list of formulas from key chapters like Solutions, Chemical Kinetics, and Electrochemistry. Essential formulas to remember:

• Arrhenius Equation
• Integrated rate equations for zero- and first-order reactions
• Molar and specific conductance
• Nernst Equation and its relation with Gibbs free energy
• Colligative properties and van 't Hoff factor
• Degree of association or dissociation

Solutions

• Osmosis, osmotic pressure, and reverse osmosis
• Henry’s law and its applications
• Positive and negative deviations from Raoult’s law

• Pseudo-first-order reactions
• Half-life period calculations
• Collision theory

• Kohlrausch’s Law
• Relationship between molar conductance and dilution
• Differences between electrolytic and galvanic cells
• Concepts of ionic and metallic conduction

Key Topics in Inorganic Chemistry

d- and f-Block Elements

• Focus on reasoning-based questions.
• Analyse trends in melting and boiling points.
• Understand lanthanoid contraction and compare lanthanoids with actinoids.
• Study the preparation and properties of KMnO₄ and K₂Cr₂O₇ using short notes.

• Differentiate between double salts and complex compounds.
• Practise nomenclature rules.
• Understand Valence Bond Theory (VBT) and Crystal Field Splitting for weak and strong field ligands.
• Learn biological applications, such as their role in medicinal chemistry and water purification.

CBSE Class 12 Chemistry Exam: Section-Wise Preparation Tips

Section A: MCQs and Assertion-Reason Questions

Multiple-choice questions (MCQs) and assertion-reason questions assess a student’s conceptual understanding rather than rote memorisation. To excel in this section, students must ensure clarity on fundamental principles, theories, and applications. Regular practice of MCQs from NCERT textbooks, sample papers, and previous years' question papers is essential. This will help in identifying common patterns and frequently asked topics.

Section B: Very Short Answer Questions

Very short answer (VSA) questions require precise and to-the-point responses. Since these answers are typically one to two sentences long, students must focus on key definitions, important formulas, and direct explanations. Highlighting crucial terms in answers can improve clarity and ensure maximum marks. Avoid adding unnecessary details, as these questions are designed to test core knowledge in a concise manner.

Section C: Short Answer Questions

Short answer questions demand structured responses with logical flow. To answer effectively, students should use bullet points, stepwise explanations, or small diagrams where needed. This section often involves problem-solving, reaction mechanisms, or reasoning-based questions, so students must ensure they cover all aspects of the question. Managing time efficiently is crucial to writing well-structured answers without spending too much time on one question.

Section D: Case-Study Based Questions

Case-study-based questions require analytical skills and the ability to apply theoretical concepts to practical situations. Students should carefully read the provided information, extract relevant details, and relate them to chemistry concepts. This section often includes real-life applications of chemistry, such as environmental chemistry, polymers, or industrial processes. Writing answers in a structured format with proper reasoning improves clarity and accuracy.

Section E: Long Answer Questions

Long answer questions require detailed explanations, diagrams, equations, and examples to justify the response. These questions often involve multi-step problem-solving, detailed reaction mechanisms, or conceptual explanations. To maximise marks, students should avoid unnecessary introductions and directly address the question with well-structured explanations. Practising long-answer questions from past papers will help in improving presentation and time management skills.