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Excel with CBSE Resources

Comprehensive resources for CBSE students' success.

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CLASS 10th ​IMPORTANT QUESTIONS

CLASS 12th IMPORTANT QUESTIONS

  1. What will be the color of the solution of copper sulphate when a small piece of zinc metal is added to it? Write the chemical equation for the reaction involved. (2024)

  2. What is the chemical name of plaster of Paris? Write the chemical equation of the reaction of plaster of Paris with water. (2024, 2025)

  3. Why is the pH in the alimentary canal of a human being in the mouth between 6.8 and 7.4? (2024)

  4. What are some common uses for baking soda? (2024)

  5. The following table shows the pH values of four solutions A, B, C and D on a pH scale: Solution A: 5, Solution B: 7, Solution C: 13, Solution D: 3. The solutions A, B, C and D respectively are of a (2025)

  6. In each of the following reactions, state what is formed when: (2025)
    (a) Dilute hydrochloric acid reacts with sodium hydroxide.
    (b) Magnesium oxide reacts with dilute hydrochloric acid.
    (c) Carbon dioxide reacts with sodium hydroxide.

  7. (a) Write a balanced chemical equation for the electrolysis of brine. (2025)
    (b) Mention two uses of any one of the products obtained in the above process.

  8. An alkaline salt 'A' is used to make a soft and fluffy cake. When it is heated, compound 'B' is formed. Write the chemical equation for the formation of compound 'B'. (2025)

  9. The pH of solution 'P' is 2 and that of solution 'Q' is 12. (2025)
    (a) Where will you place these solutions on the pH scale?
    (b) What can you add to the solution with pH 7 to increase its pH?
    (c) How many times will the concentration of hydronium ion in a solution with pH 2 be greater than that in a solution with pH 4?

  10. What is the chemical name of the compound with the formula CaOCl2 and state its use? (2025)

  11. Name the chemical compound used to remove permanent hardness of water and mention its chemical formula. (2025)

  12. When a piece of washing soda is added to dilute hydrochloric acid, a gas is evolved. What will be the observation when this gas is passed through lime water? (2025)

  13. How is sodium hydroxide manufactured from brine solution? Name the products formed. (2025)

  14. What happens when chlorine gas is passed through slaked lime? Write the chemical equation for the reaction. (2025)

  15. A student finds that the pH of two solutions A and B are 4 and 9 respectively. (2025)
    (a) Which of the two solutions is acidic?
    (b) What will be the effect on the color of red litmus paper in solution B?
    (c) Name the compound used to produce antacid medicine.

  16. A small amount of baking soda is added to vinegar in a test tube. A gas is evolved which turns lime water milky. (2025)
    (i) Name the gas evolved.
    (ii) Write the chemical equation for the reaction between baking soda and vinegar.
    (iii) What is the chemical formula and use of baking soda?

  17. Define water of crystallization. Give two examples of salts which have water of crystallization. (2025)

  18. What is the chemical name of plaster of Paris? Write the chemical equation for its preparation. (2025)

  19. Assertion (A): The dilution of concentrated nitric acid is always done by adding the acid slowly to water with constant stirring. Reason (R): Concentrated nitric acid dissolves easily in water. (2025)

  20. What is the pH of human blood? (2024)

  21. What are olfactory indicators? Give an example. (2023)

  22. Explain the role of universal indicator. (2023)

  23. When a student adds water to a concentrated acid in a beaker, he feels the beaker getting warm. Give a reason for this observation. (2023)

  24. Give two differences between an acid and a base. (2023)

  25. A student adds 1.0 g of sodium hydrogen carbonate to a beaker containing 10 mL of dilute ethanoic acid. (a) What is observed? (b) State the type of reaction. (c) Write a balanced chemical equation for the reaction. (2023)

  26. A student collected two rainwater samples, one from his village and another from a nearby industrial town. He tested the pH of both the samples and found that the pH of village rainwater was 5.6 and that of the town was 4.0. (a) What is the color of the pH paper in the village rainwater? (b) What can be the reason for the difference in the pH values of the two samples? (c) State any two harmful effects of rainwater with a pH value of 4.0. (2023)

  27. The pH of three solutions X, Y, and Z are 6, 8, and 9 respectively. Which of the following is correct? (2023)

  28. On adding a few drops of universal indicator to three unknown colorless solutions (P), (Q) and (R) taken in three separate test tubes, a student observes the color of the solutions changed to green, orange and purple respectively. (a) What are the pH values of solutions P, Q, and R respectively? (b) Arrange the solutions in increasing order of their hydrogen ion concentration. (2023)

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