CBSE Class 10 Science Exam 2025: Most Repeated Questions with Answers

The CBSE Class 10 Science exam is one of the most important exams for students, covering Physics, Chemistry, and Biology. To help students prepare efficiently, we have compiled a list of the most repeated questions based on previous years’ papers. While there is no guarantee that these exact questions will appear in the 2025 exam, preparing them thoroughly will increase the chances of scoring well.

This article provides 10 key questions, both objective and subjective, categorized under Physics, Chemistry, and Biology. Along with these questions, students must also revise the entire syllabus to ensure they are prepared for any new or unexpected questions.

CBSE Class 10 Science Exam 2025: Most Repeated Questions

Below are the most commonly asked questions in CBSE Class 10 Science exams. These questions cover important topics and concepts, ensuring students have a strong foundation.

Physics: Most Repeated Questions

What is a solenoid? How does its magnetic field pattern differ from that of a bar magnet?
- A solenoid is a coil of wire wound in a cylindrical shape that generates a magnetic field when electric current passes through it.
- The magnetic field pattern of a solenoid is similar to that of a bar magnet, with field lines emerging from one end (North Pole) and converging at the other (South Pole).
- However, unlike a bar magnet, a solenoid’s magnetic field can be controlled by changing the current.
What are the defects of vision? Explain their correction.
- The common defects of vision are:
  - Myopia (Nearsightedness): The eye can see nearby objects clearly, but distant objects appear blurred. Corrected using concave lenses.
  - Hypermetropia (Farsightedness): Distant objects are clear, but nearby objects appear blurred. Corrected using convex lenses.
  - Presbyopia: Age-related loss of focus, corrected using bifocal lenses.
  - Astigmatism: Blurred vision due to irregular cornea shape, corrected using cylindrical lenses.
State and explain Fleming’s Left-Hand Rule and Maxwell’s Right-Hand Thumb Rule.
- Fleming’s Left-Hand Rule: If you extend the thumb, forefinger, and middle finger of your left hand such that they are perpendicular to each other:
  - The thumb indicates the direction of motion.
  - The forefinger represents the magnetic field.
  - The middle finger represents the current.
- Maxwell’s Right-Hand Thumb Rule: If you hold a current-carrying conductor in your right hand with the thumb pointing in the direction of current, the curled fingers indicate the direction of the magnetic field.
State Joule’s Law and Ohm’s Law of Heating.
- Joule’s Law of Heating: The heat produced (H) in a conductor due to current flow is given by:
  - H = I²Rt, where I is current, R is resistance, and t is time.
- Ohm’s Law: The voltage (V) across a conductor is directly proportional to the current (I) flowing through it, provided temperature remains constant:
  - V = IR, where R is resistance.

Chemistry: Most Repeated Questions

What is a redox reaction? Explain with an example.
- A redox reaction is a chemical reaction where oxidation (loss of electrons) and reduction (gain of electrons) occur simultaneously.
- Example: Zn + CuSO₄ → ZnSO₄ + Cu
  - Zinc (Zn) loses electrons (oxidation) to form Zn²⁺.
  - Copper ions (Cu²⁺) gain electrons (reduction) to form Cu.
What are functional groups in carbon compounds? What is a homologous series?
- Functional Groups: Specific groups of atoms in an organic compound that determine its chemical properties (e.g., -OH for alcohols, -COOH for carboxylic acids).
- Homologous Series: A series of organic compounds with the same functional group and similar chemical properties but different molecular formulas by CH₂ units (e.g., alkanes: CH₄, C₂H₆, C₃H₈).
Explain micelle formation in water.
- Micelles are formed when soap molecules arrange themselves in a spherical structure in water.
- Each soap molecule has:
  - A hydrophobic tail (repels water, attracts oil/grease).
  - A hydrophilic head (attracts water).
- Micelles trap oil or dirt in their center, allowing them to be washed away with water.

Biology: Most Repeated Questions

What is a reflex arc? Explain its function.
- A reflex arc is the neural pathway that controls an involuntary reflex action. It includes:
  - Receptor (sense organ) → Sensory neuron → Spinal cord → Motor neuron → Effector (muscle/gland).
- Example: Pulling your hand away from a hot object. The action is automatic and does not involve the brain immediately.
What is double circulation? Explain with a diagram.
- Double circulation means blood passes twice through the heart in one complete cycle:
  - Pulmonary circulation: Blood moves from the heart to the lungs for oxygenation.
  - Systemic circulation: Oxygenated blood is pumped from the heart to the body and back.
- This system ensures efficient oxygen supply to the body.
What are plant hormones? Name the major types.

Plant hormones (phytohormones) control growth, development, and responses to stimuli.
Major types:
- Auxins: Promote stem elongation, root growth.
- Gibberellins: Help in seed germination, stem growth.
- Cytokinins: Promote cell division.
- Abscisic Acid (ABA): Inhibits growth, helps in stress response.
- Ethylene: Promotes fruit ripening.

Final Tips for CBSE Class 10 Science Exam 2025

Revise the NCERT book thoroughly, as most exam questions are based on it.
Practice previous years’ question papers to understand the pattern.
Focus on diagrams and numerical problems in Physics and Chemistry.
Memorize key definitions and formulas to save time in the exam.
Write answers in a structured manner using points, diagrams, and examples.

By preparing these most repeated questions, students can boost their confidence and score high marks in the CBSE Class 10 Science exam 2025. However, studying the entire syllabus is crucial to ensure success.

Good luck with your preparation!

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