List of top Questions asked in CBSE Class X

The colour of light for which the refractive index of glass is minimum is:
The current carrying device which produces a magnetic field similar to that of a bar magnet is:
Assertion (A): Electrons move from lower potential to higher potential in a conductor. Reason (R): A dry cell maintains electric potential difference across the ends of a conductor.
Assertion (A): Some vegetable oils are healthy. Reason (R): Vegetable oils generally have long unsaturated carbon chains.
Assertion (A): Green plants trap only 1% of the energy of sunlight that falls on their leaves. Reason (R): All green plants are the producers in a food chain.
Sometimes while running, athletes suffer from muscle cramps. Why? How is the respiration in this case different from aerobic respiration?
Write the other name given to lymph. State its two functions.
Write the formula and the molecular mass of the third homologue of alcohols. State how the boiling point of an alcohol changes as one moves from lower to higher homologues.
Copper powder is taken in a china dish and heated over a burner.Name the product formed and state its colour. Write the chemical equation for the reaction involved.
Write chemical equation for the chemical reaction which occurs when the aqueous solutions of barium chloride and sodium sulphate react together. Write the symbols of the ions present in the compound precipitated in the reaction.
Identify the organ in the human female reproductive system where the sperm encounters the egg cell. What will happen if it is blocked? Name the technique by which it can be blocked.
“The linear magnification produced by a spherical mirror is +3.”Based on this statement answer the following questions:
(a) What is the type of mirror?
(b) Where is the object located?
(c) List two properties of the image formed (other than the size/magnification).
Why is the electrolysis of water called a decomposition reaction?
Is the reaction exothermic or endothermic?
Name the gases collected at the anode and cathode.
What is the mass ratio of the gases collected at the anode and cathode?
Name the ore of mercury and state the form in which it is found in nature. Write the chemical equations along with the condition required for the reactions involved in the extraction of mercury from its ore.
Mendel crossed pure tall pea plants (TT) with pure short pea plants (tt) and obtained F₁ progeny. When the plants of F₁ progeny were self-pollinated, plants of F2 progeny were obtained.
A 2000 W heater has a resistance of about 25 Ω, whereas a 100 W bulb has a resistance of 500 Ω. When 220 V is applied on these, then which of the two
Justify your answer in each case.
Study the diagram given below and answer the questions that follow :
part of the eye
What is dispersion of white light ? State its cause. Draw a diagram to show dispersion of a beam of white light by a glass prism.
Design an experiment to demonstrate that carbon dioxide is essential for photosynthesis. Write the observation and conclusion of the experiment.
atmospheric air is being passed

In the experimental set-up shown above in diagram (I) atmospheric air is being passed into lime water with a syringe while in diagram (II) air is being exhaled into lime water. The time taken for the lime water to turn milky in both the test tubes is different. Give reason.
Draw the diagram of an open stomatal pore and label (I) Guard cells, and (II) Chloroplast on it. Mention two functions performed by stomata.
A few crystals of ferrous sulphate were taken in a dry boiling tube and heated. Tiny water droplets were observed in the tube after some time.