CBSE Class 10 Science Chapter 1 Chemical Reactions and Equations Worksheet with Answers

A chemical reaction involves the breaking of old bonds and formation of new bonds, resulting in one or more new substances with different properties. Chemical equations represent reactions using symbols and formulae. A balanced chemical equation obeys the law of conservation of mass, meaning the number of atoms of each element remains equal on both sides. NCERT Class 10 Science Chapter 1 classifies reactions into combination (two or more reactants form one product), decomposition (one reactant breaks into two or more products), displacement (a more reactive element displaces a less reactive one) and double displacement (exchange of ions between reactants). Redox reactions involve simultaneous oxidation (loss of electrons or gain of oxygen) and reduction (gain of electrons or loss of oxygen). Corrosion is the gradual degradation of metals by environmental factors, and rancidity is the oxidation of fats and oils in food, leading to unpleasant smell and taste.

This CBSE Class 10 Science Chapter 1 worksheet is designed at a moderate-to-challenging difficulty level, mirroring the 2025 CBSE board exam pattern and the variety of questions asked in recent years. Students should allocate 90 minutes to complete all sections without interruption, simulating exam conditions. The worksheet contains a total of 30+ questions distributed across multiple formats: objective MCQs to test conceptual clarity, fill-in-the-blanks for term recall, matching or true-false for quick fact checks, short-answer questions (2-3 marks each) for definitions and explanations, long-answer questions (5 marks each) for detailed processes and chemical equations, and one competency-based case-study question. Teachers can use this as a formative assessment tool after completing the chapter, while students can attempt it at home for self-evaluation using the detailed answer key provided at the end of the worksheet.

This section contains six MCQs that test your conceptual understanding of chemical reactions, balancing equations and classification of reaction types. Each question has four options; choose the most appropriate answer. These questions are drawn from across the NCERT Class 10 Science Chapter 1 syllabus, including combination, decomposition, displacement, redox, corrosion and rancidity. Pay close attention to chemical formulae, reaction conditions and definitions. MCQs are increasingly weighted in the CBSE board paper, so practising them builds speed and accuracy. Mark your answers clearly and cross-check them against the answer key at the end of this worksheet to identify gaps in your preparation and revisit NCERT notes for those topics.

This section tests your recall of key terms, definitions and chemical formulae from NCERT Class 10 Science Chapter 1. Read each sentence carefully and fill in the blank with the most appropriate word or phrase. These questions cover balancing equations, types of reactions, redox terminology, corrosion and rancidity. Precision matters — use the exact term as defined in the NCERT textbook. For example, when asked about the law governing mass in reactions, write 'law of conservation of mass' rather than a paraphrase. This format appears regularly in CBSE Class 10 Science board exams and school unit tests. After completing this section, verify each answer against the answer key and note any incorrect responses for focused revision before your next assessment or board examination.

This section presents five statements or items that you must either match to their correct pairs or mark as true or false. Carefully read each statement and apply your knowledge of chemical reactions, equation balancing and real-world applications like corrosion and rancidity. For matching questions, draw a clear line or write the correct pairing in your answer sheet. For true-false questions, write 'T' or 'F' next to each statement number. This question format tests your ability to distinguish between similar concepts, such as oxidation versus reduction, or combination versus decomposition reactions. It is a quick-scoring section if you have revised your Class 10 Science notes thoroughly. Cross-check your responses with the detailed answer key provided at the end to ensure you have understood the nuances of each concept covered in NCERT Chapter 1.

This section contains five short-answer questions, each carrying 2 to 3 marks. Write concise answers in 30 to 50 words per question, including definitions, explanations, balanced chemical equations or one example as required. These questions directly reflect CBSE Class 10 Science board exam patterns and test your ability to recall key concepts, explain processes and apply NCERT terminology accurately. For instance, when asked to define a type of reaction, state the definition clearly and support it with a balanced equation. Use proper chemical symbols and formulae — incorrect symbols will cost you marks. Practising this format builds the skill of precise, exam-focused writing. After finishing, compare your answers with the detailed answer key to refine your explanations and ensure you have not missed any essential points required by the marking scheme used in CBSE examinations across India.

This section features three long-answer or Higher Order Thinking Skills (HOTS) questions, each worth 5 marks. Allocate about 10 minutes per question and write detailed, structured answers in 80 to 100 words. These questions demand deeper understanding — you may be asked to explain a process step-by-step, compare multiple reaction types, write and balance complex equations, or apply chapter concepts to real-world situations like food preservation or metal protection. Use proper scientific terminology from the NCERT Class 10 Science textbook, draw labelled diagrams if required, and organise your answer in numbered points or short paragraphs for clarity. HOTS questions reward students who can analyse, synthesise and evaluate information, not just recall facts. After completing this section, review the answer key carefully to see model answers and mark allocation, which will help you improve answer writing for the CBSE board exam in March 2025.

Competency-based case-study questions were introduced by CBSE in 2023 and now form part of every board exam. This section presents a short real-world scenario or experimental observation related to chemical reactions and equations, followed by four sub-questions (usually two MCQs and two short-answer). Read the case study carefully, underline key facts and apply your understanding of NCERT Class 10 Science Chapter 1 concepts to answer. These questions test your ability to interpret data, analyse situations and apply theoretical knowledge practically. For example, a case might describe an experiment on rusting, food spoilage or a displacement reaction observed in the laboratory. Each sub-question carries 1 mark. This format builds critical thinking and is increasingly common in CBSE assessments. Use the answer key to check your responses and understand the reasoning behind each correct answer, which will prepare you for similar questions in board and competitive exams.

Below is the full answer key for every question in this CBSE Class 10 Science Chapter 1 worksheet. Each answer is accompanied by a brief explanation or step-by-step working to help you understand the reasoning. Use this section for self-assessment: award yourself marks honestly, identify weak areas and revisit the corresponding NCERT Class 10 Science notes or solved examples. If you score below 70 percent, revise the chapter thoroughly before attempting the worksheet again. For conceptual doubts or instant clarifications on any question, you can upload a photo of your work to CBSETUTOR.ai, where a 24×7 AI tutor provides step-by-step solutions and explanations for every CBSE subject and chapter. CBSETUTOR.ai offers a flat subscription of ₹999 per month for all classes 6 to 12, with a 3-day free trial, making it an affordable alternative to expensive city coaching centres. Parents across metros and Tier-2 cities rely on it for round-the-clock homework help and exam prep support.

To maximise learning, attempt this CBSE Class 10 Science Chapter 1 worksheet in one sitting under timed conditions — set a 90-minute timer and work without consulting notes or textbooks. This simulates the board exam environment and builds stamina. After finishing, take a 10-minute break, then use the answer key to mark your own work. Award full marks only when your answer matches the key in content and terminology; partial marks are acceptable for short-answer questions if key points are covered. Calculate your total score and identify the question types or topics where you lost marks — for instance, if you struggled with balancing equations, revisit NCERT examples and practice more. Repeat the worksheet after a week to measure improvement. Teachers can print copies for the entire class and conduct a class test, then discuss common errors collectively. Parents should encourage children to maintain a mistake log, writing down every incorrect answer with the correct explanation, which becomes a personalised revision resource before board exams.

Chemical Reactions and Equations is Chapter 1 of CBSE Class 10 Science for a reason — it is the conceptual backbone for physical chemistry topics throughout the year. Understanding how to balance equations correctly is essential for solving numericals in Acids, Bases and Salts (Chapter 2) and Metals and Non-Metals (Chapter 3). The CBSE Class 10 board paper typically carries 3 to 5 marks directly from this chapter in the form of MCQs, assertion-reason questions, short answers and one long answer or case study. In the 2024 board exam, two MCQs on types of reactions and one 3-mark question on redox were asked. Additionally, balancing equations appears as a sub-part in questions from later chapters. Rancidity and corrosion are favourite application-based topics for 2-mark questions. Students who master this chapter early gain confidence and speed, which translates into higher overall scores. Regular practice with worksheets like this one, combined with NCERT back exercises and previous years' question papers, ensures thorough preparation and reduces exam-day anxiety.