Chemistry 1st Year Chapter 1 Basic Concepts Notes MCQs Bank

chemistry 11th notes chapter 1

1. Which of the following will form single peak in mass spectrograph:

 
 
 
 

2. What is the mass of one mole of Iodine:

 
 
 
 

3. Actual yield of a chemical reaction is always less than theoretical yield because:

 
 
 
 

4. How many electrons have to be removed to ionize 1.0 x 10⁻⁶ mol of Ne atoms to Ne+ ions in a neon advertising tube?

 
 
 
 

5. 5604 cm³ of H₂ gas at STP contains of hydrogen:

 
 
 
 

6. Mass of sodium in 53 g of Na₂CO₃ is:

 
 
 
 

7. 0.5 moles of H₂SO₄ contains “X” moles of oxygen atoms “X” is:

 
 
 
 

8. A compound contains 50% sulphur and 50% oxygen by mass. The empirical formula of the compound is:

 
 
 
 

9. % of the nitrogen in urea (NH₂CONH₂):

 
 
 
 

10. One mole of SO₂ contains:

 
 
 
 

11. 20 moles each of Mg and O₂ react to form MgO. The amount of MgO formed would be:

 
 
 
 

12. Equal volumes of CO and N₂ are taken in identical conditions, The correct relationship between masses of two gases is?

 
 
 
 

13. Percentage of oxygen in H₂O is:

 
 
 
 

14. The number of peaks obtained in mass spectrometry shows:

 
 
 
 

15. Combustion analysis is performed for the determination of:

 
 
 
 

16. The least no of molecules is present in 30 g of:

 
 
 
 

17. Who first of all determined atomic masses of elements:

 
 
 
 

18. The atomicity of one molecule of Haemoglobin is:

 
 
 
 

19. A sample in the ionization chamber of mass spectrometer is ionized by:

 
 
 
 

20. Large no of isotopes are known for the elements whose masses are multiple of:

 
 
 
 

21. Which of the following compounds has the highest % age of oxygen by weight?

 
 
 
 

22. The volume occupied by 2.0 g of Ne at STP:

 
 
 
 

23. The height of the peak in mass spectrum shows:

 
 
 
 

24. 180 g of glucose contains number of hydrogen atoms:

 
 
 
 

25. The mass of H-atom is 1.008 a.m.u. Its mass in kg should be

 
 
 
 

26. The mass of one mole of electron is:

 
 
 
 

27. Relative atomic mass is the mass of an atom of an element as compared to the mass of one atom of:

 
 
 
 

28. A smuggler was caught by Airport police and 24 g of diamond was recovered from him. How many atoms of carbon he was carrying?

 
 
 
 

29. Which one of the following is not a molecular ion:

 
 
 
 

30. How many atoms of carbon are present in 18 g of glucose C₆H₁₂O₆:

 
 
 
 

31. Atoms of all the elements always contain in nucleus:

 
 
 
 

32. The number of moles of NO₂ which contains 16 g of oxygen:

 
 
 
 

33. Which of the following not has equal number of atoms as that in 6g Molybdenum (Ar : 96)

 
 
 
 

34. Which of the following elements has nine isotopes:

 
 
 
 

35. CO+ is an example of:

 
 
 
 

36. Which one is a monoisotopic element?

 
 
 
 

37. One mole of potassium chlorate is thermally decomposed and excess of aluminum is burnt in the gaseous mixture. How many moles of aluminum oxide is formed? Respective equations are given as:
2KClO₃ → KCl + 3O₂ 4Al + 3O₂ → 2Al₂O₃

 
 
 
 

38. Which one of the following is not the mono isotopic element:

 
 
 
 

39. The technique that is not used to separate isotopes is:

 
 
 
 

40. When 0.5 moles of Al₂(SO₄)₃ are dissolved in water, the total number of particles produced?

 
 
 
 

41. In a mass spectrometer, increasing the magnetic field strength with constant electric field results in?

 
 
 
 

42. Which one of the following substances is used as CO₂ absorber in combustion analysis:

 
 
 
 

43. Formation of uninegative ion is:

 
 
 
 

44. Gram atoms of hydrogen in 5.5g H₂:

 
 
 
 

45. Number of H⁺ ions when 0.1 mole of sulfuric acid is completely ionized in water:

 
 
 
 

46. 27 g of Al will react with how much mass of O₂ to produce Al₂O₃:

 
 
 
 

47. Which one of the following pair is not iso-electronic:

 
 
 
 

48. Mg reacts with HCl as per the following reactions:
Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)
Given that; Mg = 21g and HCl = 21g, the excess reactant is;

 
 
 
 

49. Which of the following ion formation is always exothermic:

 
 
 
 

50. During combustion analysis, which one is used for absorbing carbon dioxide?

 
 
 
 

51. Mass in grams of 10 moles of aspartame (Cl₄H₁₈N₂O₅):

 
 
 
 

52. Which one of the following contains maximum no. of molecules:

 
 
 
 

53. The number of electrons in one mole of H₂ is:

 
 
 
 

54. Molecular mass of water (18 g) means:

 
 
 
 

55. Molecular ions are produced in the mass spectrometer. Which type of molecular ions is more abundant?

 
 
 
 

56. The mass of 0.5 mole of Aluminium is:

 
 
 
 

57. The largest number of moles are present in:

 
 
 
 

58. The stoichiometric calculations for a chemical reaction results in:

 
 
 
 

59. An organic compound contains 2 percent of sulphur. The molar mass of compound is:

 
 
 
 

60. 1 gram formula refers to:

 
 
 
 

61. Which of the following contains 1 mole of the stated particle?

 
 
 
 

62. What will weigh more:

 
 
 
 

63. Percentage of oxygen in calcium carbonate is:

 
 
 
 

64. Number of moles present in 0.6 grams of silica is (Atomic mass Si = 28, O = 16)?

 
 
 
 

65. The separation of different isotopes in the mass spectrometer is done on the basis of:

 
 
 
 

66. The relative atomic mass of oxygen according to C -12.000 a.m.u standard is:

 
 
 
 

67. In a mass spectrometer, increasing the electric field with constant magnetic field results in:

 
 
 
 

68. Which one of the following properties is always in whole number:

 
 
 
 

69. The number of isotopes of elements with even mass number and even atomic number are:

 
 
 
 

Short Questions

1. 180 grams of glucose and 342 grams of sucrose have same number of molecules but different number of atoms present in them. justify it?
2. 23g of NA and 238g of U have equal number of atoms in them.How?
3. 414 dm³at STP although the sizes and masses of molecules of three gases are very different from each other.Give reason?
4. 9 g of H₂SO₄,when completely ionized in water have equal number of positive and negative charge but number of positively charged ions are twice the number of negatively charged ions.Give reason?
5. 96 gm of SO₄⁻² has Avogadro’s number of SO₄⁻² ions twice the Avogadro’s number of negative charges 4NA as oxygen atoms and 5NA as total number of atoms.How?
6. Calculate the mass in kg of 2.6×10²³ molecules of SO₂?
7. Calculate the number of moles of o-atoms in 9 g of Mg(NO₃)?
8. Circulate the mass in grams of 10⁻³ mole of water?
9. Concept of limiting reactant is not applicable to the reversible reactions?
10. Define Avogadro’s number?How does it relate to the masses of chemical substances?
11. Define empirical formula and how it is related to molecular formula?When they are same for a molecule?
12. Define storchiometry.What are its basic assumptions?
13. Distinguish between actual and theoretical yield. Calculate efficiency of a reaction?
14. How can the efficiency of a chemical reaction be expressed?
15. How does the change of either electric field or magnetic field help us to record the isotopic separation by mass spectrometer?
16. How many water molecular are there in 10 g of ice?
17. In the mass spectrum of isotopes of oxygen the highest peak is due to ₈O¹⁶,the second highest is of ₈O¹⁸ while ₈O¹⁷ has the smallest peak.Why?
18. Law of conservation of mass has to be obeyed in stiochimetric calculations?
19. Mg atom is twice heavier than that of carbon atom.How?
20. Molecular formula is multiple of empirical formula.Give an example?
21. N₂ and CO have same number of electrons protons and neutrons.Justify?
22. NaCI has 58.5 amu as formula mass and not the molecular mass justify it?
23. No individual neon atom in the sample of the element has a mass of 20.18 a.m.u.Why?
24. One hundred ions of NO₃⁻ and fifty ions of SO₄⁻² have equal number of charges but they have unequal masses and unequal number of atoms in them individually.Justify it?
25. One mole of H₂O has two moles of bonds three of atoms ten moles of electrons and twenty –eight moles of the total fundamental particles present in it.Justify?
26. One mole of H₂SO₄ should completely react with two moles of NaOH.How does Avogadro’s number help to explain it?
27. Prove that one mole of each N₂,CO₂,and H₂ contain equal number of molecules?
28. The atomic masses may be in fractions.Why?
29. The ratio of heights of the peaks for the isotopes of chlorine is 3:1 but in case of bromine two peaks of equal heights are obtained.Why?
30. The reaction of combustion in atmosphere consumes O₂,which is in excess.What is limiting reactant?
31. What do you mean by molecular ions?
32. What is atomic mass unit?
33. What is limiting reagent?How it helps t⁰Control the reaction?
34. What is mass spectrum or mass spectrograph?
35. What is the function of electrometer in separation of isotopes in mass spectrometer?
36. What is the mass and number of molecules of CO₂ in 0.224 dm³ of CO₂ at S.T.P?
37. What is the number of covalent bonds in 8 g of CH₄?
38. What is the number of H⁺ in 8g of H₃PO₄?
39. What is the reason for two equally strong peaks in the mass spectrum for bromine;while for iodine only one peak at 127 a.m.u. is indicated?
40. Whenever an electron is removed from the atom a cation is produced and the formation of the cation is an endothermic process.Comment?
41. Which is the limiting reactant?
42. Why positively charged ions of isotopes are passed through magnetic field in the mass spectrometer?
43. Why the experimental yield is mostly less than the theoretical yield?
44. Why the isotopes have the same chemical properties?

Long Questions

“1. Differentiate between:
i. Atom and Gram atom
ii. Mole and molecule
iii. Formula weight and molecular weight
iv. Empirical formula and molecular formula”
2. The empirical formula of a compound is CH₂O. If the molecular weight of the compound is 180, calculate the molecular formula.
3. How many molecules of water are present in 5.4 grams of H₂O?
4. A given compound contains C = 60%, H = 13.0% and 0 = 27%. Calculate its empirical formula.
“5. Calculate the volume of oxygen at S.T.P. that may be obtained by complete decomposition of 51.3 gm of KClO₃ on heating in presence of MnO₂ as a catalyst(At. Mass of K = 39; Cl = 35.5;O = 16; Mn = 55)
2KClO₃ –> 2KCl + 3O₂”
“6. Define the following:
i. Limiting Reactants ii. Significant Figure iii. Bond Energy”
“7. Compare the rates of diffusion of the following pairs of gases:
i. H₂ and D₂ ii. CH₄ and He iii. SF₆ and SO₂ “
“8. 54 gm of dinitrogen pent oxide (N₂O₅) is decomposed on heating as under:
2N₂O₅—-> 4NO₂ + O₂
Find out the volume of NO₂ and O₂ at S.T.P. “
9. In a collection of 24×10²⁵ molecules of C₂H₅OH what is the number of moles?

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