Sunday, January 22, 2012

CBSE Class 7 Solved Objective Questions Chapter - Acids, Bases and Salts (MCQs)

CBSE Class 7 Solved Objective Questions  Chapter - Acids, Bases and Salts MCQs

1. The word acid comes from the Latin word ------ which means sour.( acere)

2. The substances used to test whether a substance is acidic or basic are known as ----(indicators)

3. The most commonly used natural indicator is litmus paper . It is extracted from ----(lichens)

4. In acidic solution, litmus paper turns into ------(red)

5. In basic solution, litmus paper turns into ------(blue)

6. In distilled water , litmus paper turns into ------(purple)

7. China rose indicator turns acidic solutions ------and basic solutions to ------ [dark pink (magenta) , green]

8. The reaction between an acid and a base is known as ----- [neutralization]

9. Salt and water are produced in neutralization process with the evolution of heat.[ water]

10. H C l + N a O H ---->      ------- + H2O

11. Our stomach contains -------. It helps us to digest food[hydrochloric acid]

12. indigestion is painful so to relieve indigestion, we take an antacid such as milk of magnesia , which contains ------- [magnesium hydroxide]

13. The sting of an ant contains ---------[ formic acid]

14. The effect of the sting can be neutralized by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains ------- [zinc carbonate]

15. When the soil is too acidic, it is treated with ---------------[ bases like quick lime (calcium oxide) or slaked lime (calcium hydroxide)]

16. Ammonia is found in many household products, such as window cleaners. It turns red litmus blue. its nature ---------------------- [Basic]

17. The wastes of many factories contain-------- [ acids]

18. Blue litmus paper is dipped in a solution. It remains blue. -------- is the nature of the solution. [basic]

19. Proteins that build part of our cells are made up of------ [amino acids]

20. The fats in our body contain ------ [fatty acids]

21. Each cell in our body contains an acid called ---------- [the deoxyribonucleic acid]

22. ----------- is common to all acids?[hydrogen ion]

23. ------ gas evolved when dilute sulphuric acid acts on sodium carbonate[CO2]

24. Acids do not show acidic behavior in absence of water because ------ dissociates from an acid only in in presence of water .[ hydrogen ions]

25. ---- base is also used in soda-acid fire extinguishers.[ Baking Soda]

26. -------- gas is usually liberated when an acid reacts with a metal [ H2]

27. The hydrogen ions combine with H2O to form ------------- [ hydronium ions (H3O+)]

28. Aqueous solution of acid conduct electricity due to -------- present in it. [ ion]

29. ------------ is the common name of the compound CaOCl2 [Bleaching powder]

30. -------------- is Universal Indicator [ pH Scale]

31. pH is the measure of Acidity or Alkalinity of a solution. The term pH stands for ----------[“Potential of hydrogen”]

32. If the pH rain water drops below ----------------. it is called acid rain[5.6]

33. The bases that dissolve in water are known as -----------[ alkalies]

34. Aqueous solution of sodium chloride (NaCl) is known as -------------[ Brine]

35. Salts containing water molecules in their crystal form are called --------- [hydrated salts]

36. water molecules present in salt s known as ------------ [‘water of crystallization’]

37. Phenolphthalein become colourless in ---- and pink in ------[ Acid, base]

38. --------- is the colour of methyl orange in acidic solution.[ pink]

39. ------------ and ------- acid are present in vinegar and lemon.[ acetic acid, citric acid]

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