Board exams are rarely about unearthing completely new questions; they are about testing core concepts that reappear in varying formats every year. By analyzing the last ten years of papers, we have identified that approximately 30% of the Science paper consists of high-frequency questions. Mastering these "Most Repeated Questions" allows students to secure safe marks early and focus their mental energy on higher-order thinking problems. This guide provides a curated list of top repeated questions across Physics, Chemistry, and Biology to streamline your CBSE Class 10 preparation.

Why Repeated Questions Matter in CBSE Science

For a Class 10 student, the sheer volume of the Science syllabus can be overwhelming. However, CBSE follows a specific blueprint that prioritizes certain "evergreen" topics. Focusing on Class 10 Science repeated questions is not a shortcut; it is a tactical strategy. It ensures that you are perfectly aligned with what the examiners consistently consider essential.

By studying CBSE Class 10 previous year questions, you notice that while the numerical values change, the logic remains identical. Here is a breakdown of the 20 most frequent questions you will encounter.

Most Repeated Physics Questions

Physics in Class 10 is divided between "Light" and "Electricity." These chapters carry the highest weightage for numericals and conceptual diagrams.

1. Ohm’s Law & Resistance: State Ohm’s Law and solve numericals on resistors in series and parallel. (Frequently asked as a 5-mark question).
2. Joule’s Law of Heating: Explain the heating effect of electric current and its applications in household appliances like fuses and heaters.
3. Lens and Mirror Formula: Calculate the position, nature, and magnification of images using the Mirror Formula (1/f = 1/v + 1/u) and Lens Formula (1/f = 1/v - 1/u).
4. Ray Diagrams: Draw ray diagrams for a concave mirror when the object is at 'C' or between 'F' and 'P'.
5. Refraction through Glass Slab: Trace the path of a ray of light passing through a rectangular glass slab and label the lateral shift.
6. Magnetic Field of a Solenoid: Describe the pattern of magnetic field lines around a current-carrying solenoid.
7. Fleming’s Left-Hand Rule: State the rule and explain its application in an electric motor.

Most Repeated Chemistry Questions

Chemistry focuses heavily on reactions, properties of compounds, and the pH scale.

1. Balancing Chemical Equations: At least one 3-mark question always requires balancing equations (e.g., Photosynthesis or Respiration equations).
2. Types of Chemical Reactions: Differentiate between Displacement and Double Displacement reactions with examples like the reaction between Iron nails and Copper Sulphate.
3. pH in Daily Life: Explain the importance of pH in the digestive system or tooth decay.
4. Properties of Acids and Bases: Reaction of Zinc with dilute Sulphuric acid (testing for Hydrogen gas).
5. Metals and Non-metals (Extraction): Differentiate between Roasting and Calcination with chemical equations.
6. Homologous Series: Define a homologous series and its characteristics in Carbon compounds.
7. Saponification vs. Esterification: Write the chemical equations for the formation of soap and esters.

Most Repeated Biology Questions

Biology is the "Diagram Heavy" section of the paper. Labeling accuracy is as important as the theory itself.

1. Human Digestive System: Draw a neat, labeled diagram and explain the role of enzymes like Pepsin and Trypsin.
2. Aerobic vs. Anaerobic Respiration: Compare the breakdown of glucose in various organisms (the "Glucose Pathway" flowchart).
3. Transportation in Humans: Describe the double circulation of blood and why it is necessary for birds and mammals.
4. Asexual Reproduction: Explain Binary Fission in Amoeba and Budding in Hydra with diagrams.
5. Male and Female Reproductive Systems: Labeling diagrams and explaining the function of the placenta and ovaries.
6. Mendel’s Monohybrid Cross: Explain the 3:1 ratio in the F2 generation using pea plants.

Chapter-wise Distribution of Repeated Questions

Not every chapter is created equal. Infinity Learn’s micro-analysis reveals that a small number of chapters contribute to a large chunk of the repeated questions.

How to Practice Repeated Questions

1. Use the "NCERT First" Rule: 95% of repeated questions are lifted directly from NCERT in-text questions and back exercises.
2. Solve Sample Papers: After finishing a chapter, solve the last 5 years of CBSE Class 10 Science important questions for that specific topic.
3. Active Recall for Diagrams: Don't just look at diagrams; draw them from memory five times until the labeling becomes second nature.
4. Flashcards for Formulas: Keep a list of all Physics formulas and Chemistry valency tables on your study desk.

Tips to Score Full Marks in Science

• Keyword Precision: Examiners look for specific terms like "Exothermic," "Refractive Index," or "ATP." Ensure these are highlighted in your answers.
• Neatness: Use a sharp pencil for diagrams. A cluttered diagram often loses marks even if it is technically correct.
• Bullet Points: Never write long paragraphs. Breakdown your answer into logical points to make it "scannable" for the checker.

Mastering the Top 20 most repeated questions gives you a psychological edge. It provides a safety net of marks, allowing you to approach the trickier, case-based questions with confidence. Remember, the board exam is a test of consistency, not just intelligence. Follow the Infinity Learn philosophy: Learn the concept, practice the repeaters, and assess your speed daily.