Explore Key Experiments and Lab Techniques for Scoring High in Class 10 Science
FAQs on Essential Science Practicals and Project Ideas for CBSE Class 10 (2025-26)
1. What is the marks distribution for the CBSE Class 10 Science practical exam for the 2025-26 session?
For the 2025-26 session, the Science practical exam holds a weightage of 20 marks as part of the internal assessment. The marks are generally distributed as follows:
- Conducting two experiments (one from Physics, one from Chemistry/Biology): 8 marks
- Practical record (lab manual) and submitted project work: 7 marks
- Viva-voce (oral questions) based on experiments and the project: 5 marks
2. What are some frequently asked questions from the experiment to find the focal length of a concave mirror and convex lens?
Important questions for this experiment test your understanding of optics concepts. Be prepared for questions such as:
- What is the difference between a real and a virtual image?
- What are the necessary precautions to avoid parallax error while recording observations?
- Why should the object (candle) and screen be kept at the same height as the centre of the lens/mirror?
- Define key terms like principal axis, pole, and centre of curvature.
- How would the result be affected if a portion of the mirror or lens is covered?
3. Which diagrams are considered most important for the Biology practicals in the Class 10 exam?
Drawing and labelling skills are crucial for scoring well. The most important diagrams to practise for Class 10 Biology practicals are:
- The structure of a stomatal pore (both open and closed) as seen in a leaf peel.
- Asexual reproduction methods like Budding in Yeast and Hydra.
- The process of Binary Fission in Amoeba, showing the stages of division.
- The experimental setup to demonstrate that CO2 is released during respiration.
4. How can a student choose a high-scoring science project topic for the Class 10 board assessment?
To select a science project that scores high marks, focus on a topic that is:
- Syllabus-Relevant: It should be based on a concept from your NCERT Science textbook.
- Investigatory: A project that tests a hypothesis and presents a conclusion (e.g., 'Effect of different light colours on plant growth') scores better than a simple static model.
- Original and Creative: It should demonstrate independent thinking.
- Well-Documented: The project report must have a clear objective, procedure, observations, and conclusion.
5. What are the most common mistakes that lead to a loss of marks in Chemistry practicals?
Students often lose marks in Chemistry practicals due to simple errors. Key mistakes to avoid include:
- Contamination: Using wet or unclean test tubes, which can alter the results of a chemical reaction.
- Incorrect Measurement: Not reading the meniscus level correctly in a measuring cylinder.
- Faulty Observation: Misidentifying the colour of a precipitate or the smell of a gas.
- Ignoring Safety: Not handling acids or heating substances correctly, which is a major point of questioning in the viva.
- Unbalanced Equations: Failing to write the correct, balanced chemical equation for the reaction performed.
6. Why is a thorough understanding of the reactivity series essential for scoring well in the displacement reaction experiment?
The reactivity series is the fundamental principle behind the displacement reaction experiment. A strong understanding is crucial because examiners will probe your knowledge with questions like:
- Why does the blue colour of copper sulphate solution fade when an iron nail is dipped in it?
- What would you observe if a strip of copper was placed in a zinc sulphate solution? Explain why.
- Arrange the four given metals in the correct order of decreasing reactivity based on your experimental results.
7. What are some expected viva-voce questions for the experiment to verify Ohm's law?
For the Ohm's law experiment, the viva questions test both your theoretical and practical knowledge. Important questions include:
- State Ohm's Law and its conditions.
- What is the function of the rheostat in the circuit?
- Why is an ammeter always connected in series and a voltmeter in parallel?
- What physical quantity does the slope of a V-I graph represent?
- What are the most common sources of error in this experiment?
8. How do the experiments on ethanoic acid and saponification serve as important questions?
These experiments are important because they cover key concepts from the 'Carbon and its Compounds' chapter. Expect questions related to:
- Properties of Ethanoic Acid: Its characteristic vinegar-like smell, its solubility, and its acidic nature (turning blue litmus red).
- Reaction with Carbonates: A key test is the reaction of ethanoic acid with sodium carbonate/bicarbonate, which produces brisk effervescence due to CO₂ gas.
- Saponification: The basic process of soap formation. A very important question is why common salt (NaCl) is added, which is to cause the precipitation of soap.
