#### Most expected three mark questions in Basic Concepts of Chemistry and Chemical Calculations

11th Standard

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Chemistry

Answer any 50 of the following questions
Time : 02:00:00 Hrs
Total Marks : 150

Part - A

50 x 3 = 150
1. Classify the following species into acids and bases according to Lewis concept.
S2-, H+, OH-, BF3' Ni2+, F-

2. MnO42- undergoes disproportionation reaction in acidic medium but MnO4- does not. Give reason.

3. Categorise the redox reactions that occur in our daily life

4. 2Cu2S + 3O2 $\longrightarrow$ 2Cu2O + 2SO2
(i) In this reaction which substance is getting oxidised and which substance is getting reduced?
(ii) Name the oxidising and reducing agents.

5. How would you know whether a redox reaction is taking place in an acidic, alkaline or neutral medium?

6. What is the most essential conditions that must be satisfied in a redox reaction?

7. Why is anode called oxidation electrode, whereas the cathode is called reduction electrode?

8. Zn rod is immersed in CuSO4 solution. What will you observe after an hour? Explain you observation in terms of the redox reaction.

9. Nitric acid is an oxidising agent and reacts with PbO but it does not react with PbO2 Explain why?

10. Which one of the two, ClO2- or ClO4- shows disproportionation reaction and why?

11. Consider the reactions,
(i) H3PO2(aq) + 4AgNO3(aq)+ 2H2O(l) $\longrightarrow$ H3PO4(aq)+ 4Ag(s)+ 4HNO3(aq)
(ii) H3PO2(aq) + 2CuSO4(aq) + 2H2O(l) $\longrightarrow$ H3PO4(aq)+ 2Cu(s) + H2SO4(aq)
(iii) C6H5CHO(l) + 2[Ag(NH3)2]+(aq) + 3OH-(aq)  $\longrightarrow$ C6H5COO-(aq) + 2Ag(s)+ 4NH3(aq) + 2H2O(l)
(iv) C6H5CHO(l) + 2Cu2+(aq) + 5OH-(aq) $\longrightarrow$ No change observed.
What interference do you draw about the behavior of Ag+ and Cu2+ from these reactions?

12. 'X' is an impure substance. Is it an element, compound or mixture?

13. What are the basic properties used to identify a substance?

14. Why is distilled water a compound whereas tap water is a mixture?

15. Mixture of salt and water is a solution while that of oil and water is not. Explain

16. Why is air sometimes considered as a heterogeneous mixture?

17. By applying the knowledge of chemical classification, classify each of the following into elements, compounds or mixtures
(i) Sugar
(ii) Sea water
(iii) Distilled water
(iv) Carbon dioxide
(v)  Copper wire
(vi) Table salt
(vii) Silverplate
(viii) Naphthalene balls

18. Matter is defined as anything that has mass and occupies space. All matter is composed of atoms

19. Write a note on the differences between elements and compounds

20. Write a note on 'mixture' based on the chemical classification of matter.

21. How will you classify matter based on physical state?

22. Explain the classification of matter based on chemical composition.

23. Draw a flow chart to illustrate classification of matter.

24. Calculate the number of atoms in the following.52 g of He

25. Calculate the number of atoms in the following.52 moles of He.

26. Calculate the mass of the following: 1 atom of silver

27. Calculate the mass of the following: 1 molecule of benzene

28. Calculate the mass of the following: 1 molecule of water.

29. One million silver atoms weigh 1.79 x 10-16 g. Calculate the atomic mass of silver.

30. How much mass (in gram units) is represented by the following?
0.2 mol of NH3

31. How much mass (in gram units) is represented by the following?
3.0 mol of CO2

32. How much mass (in gram units) is represented by the following?
5.14 mol of H5IO6

33. Calculate the Formula Weights of the following compounds.NO2

34. Calculate the Formula Weights of the following compounds.C6H12O6 - Glucose

35. Calculate the Formula Weights of the following compounds.NaOH

36. Calculate the Formula Weights of the following compounds.Mg(OH)2

37. Calculate the oxidation number of nitrogen in nitrous acid and nitric acid

38. How many moles of barium sulphate is precipitated when 1 mole of aluminium sulphate reacts completely with barium chloride?

39. Calculate the mass of the atom in amu

40. Calculate the oxidation number of underlined atoms of the following:
K2MnO4

41. Calculate the oxidation number of underlined atoms of the following:
K2CrO4

42. Calculate the oxidation number of underlined atoms of the following:
NO3-

43. What mass of N2 will be required to produce 34g of NH3 by the reaction, N2 + 3H2 $\longrightarrow$ 2NH3·

44. Calculate the equivalent weight of H3PO4 and Ca(OH)2 on the basis of given reaction.
H3PO4 + NaOH $\longrightarrow$ NaH2PO4 + H2O
Ca(OH)2 + HCI $\longrightarrow$ Ca(OH)CI + H2O

45. Calculate the gram molecular mass of sugar having molecular formula C12H22O11

46. Calculate (a) The mass of 0.5g molecule of sugar and (b) Gram molecule of sugar in 547.2 g

48. Define molar volume

50. Define atomicity.

51. Which law co-relates the mass and volume of a gas?

52. Does one gram mole of a gas occupy 22.4 Lunder all conditions of temperature and pressure

53. Bring about the dissimilarities in mole concept and molar mass by clearly analysing them