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In CBSE Class 10 Board Exams, questions based on the reactions and diagrams form an essential part of the Science question paper. Every year, 8-9 questions are jointly asked on the basis of chemical reactions and diagram construction. So, student must revise all important chemical reactions, equations and diagrams involved in Chemistry, Physics and Biology parts of CBSE Class 10 Science. To help all students in quick and effective revision before their Science exam, we have assembled all important chemical reactions and diagrams from NCERT Science. We have prepared separate articles for chemical reactions and diagram constructions wherein we have included all relevant and important concepts involved in Chemistry, Physics and Biology. Links to these important resources are provided below:

Previous Years’ Questions Based on Class 10 Science Chemical Reactions and Diagrams

When we analysed the previous years’ CBSE Class 10 Science question papers to see how many questions in papers were based on chemical reactions and diagrams. About 30% of the questions were of such type where either students had to write chemical equations involved in a particular reactions or identify the compounds involved in a reaction. In others, they were required to construct a labelled diagram or identify different parts in a given diagram.  You can check below such questions asked in the previous years (2018-2019):

Questions based on chemical reactions from previous year papers:

1. 2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for sometime. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical equation.

2. Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation for the reactions.

(a) Zinc reacts with silver nitrate to produce zinc nitrate and silver.

(b) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

3. A compound ‘X’ on heating with excess conc. Sulphuric acid at 443 K gives unsaturated compound ‘Y’. ‘X’ also reacts with sodium metal to evolve a colourless gas ‘Z’. Identify ‘X’, ‘Y’ and ‘Z’. Write the equation of the chemical reaction of formation of ‘Y’ and also write the role of sulphuric acid in the reaction.

4. Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactions. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity.

5. 2 mL of sodium hydroxide solution is added to a few pieces of granulated zinc metal taken in a tent tube. When the contents are warmed, a gas evolves which is bubbled through a soap solution before testing. Write the equation of the chemical reaction involved and the test to detect the gas. Name the gas which will be evolved when the same metal reacts with dilute solution of a strong acid.

6. How is copper extracted from its sulphide ore? Explain the various steps supported by chemical equations. Draw labelled diagram for the electrolytic refining of copper.

Questions based on Biology diagrams from previous year papers:

1. Identify the given diagram. Name the parts 1 to 5:

2. If the image formed by a spherical mirror for all positions of the object placed in front of it is always erect and diminished, what type of mirror is it? Draw a labelled ray diagram to support your answer.

3. Draw excretory system in human beings and label the following organs of excretory system which perform following functions:

i. form urine.

ii. is a long tube which collects urine from kidney.

iii. stores urine until it is passed out

4. Name the process by which an amoeba reproduces. Draw the various stages of its reproduction in a proper sequence.

5. A student is viewing under a microscope a permanent slide showing various stages of asexual reproduction by budding in yeast. Draw diagrams of what he observes. (in proper sequence)

6. Define an ecosystem. Draw a block diagram to show the flow of energy in an ecosystem

7. Trace the sequence of events which occur when a bright light is focused on your eyes.

8. A student is observing the temporary mount of a leaf peel under a microscope. Draw labelled diagram of the structure of stomata seen under the microscope.

9. Draw a labelled diagram in proper sequence to show budding in hydra.

Questions based on Physics diagrams from previous year papers:

1. What is a rainbow? Draw a labelled diagram to show the formation of a rainbow.

2. An object of height 4.0 cm is placed at a distance of 30 cm from the optical centre ‘O’ of a convex lens of focal length 20 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre ‘O’ and principal focus ‘F’ on the diagram.

3. Draw magnetic field lines produced around a current carrying straight conductor passing through a cardboard. Name, state and apply the rule to mark the direction of these field lines.

To check more of such questions and know different ways in which these questions can be asked in the upcoming exam, check the following link: