Analytical Chemistry Mc Questions

HKDSE Chemistry  A Modern View Part XV Analytical Chemistry

Multiple Choice Questions

Section 63.1 1. Which of the following combinations concerning c oncerning an ion in aqueous solution and its i ts corresponding colour is correct? Ion

Colour

A.

Copper(II) ion

Green

B.

Dichromate ion

Orange

C.

Iron(II) ion

Yellow

D.

Permanganate ion

Very pale pink

Section 63.2 2. What is the flame colour of potassium chloride when it is heated in a Bunsen flame? A.

Brick-red

B.

Bluish green

C.

White

D.

Lilac

Section 63.3 3. Which of the following hydroxides can dissolve in excess ammonia solution? (1) Zinc hydroxide (2) Aluminium hydroxide (3) Copper(II) hydroxide A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

4. Which of the following statements concerning copper(II) compounds are correct? (1) Copper(II) hydroxide can dissolve in excess ammonia ammonia solution. solution. (2) Copper(II) hydroxide hydroxide cannot dissolve in excess sodium hydroxide solution. (3) Copper(II) compounds compounds will give bluish green flame when heated in Bunsen flame. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

1


5. Which of the following compounds does NOT form a precipitate with excess ammonia solution? A.

Iron(II) chloride

B.

Magnesium nitrate

C.

Copper(II) sulphate

D.

Aluminium iodide

Section 63.4 6. What would be observed when potassium carbonate is heated? A.

A brick-red flame is observed

B.

A black solid is formed.

C.

A gas which turns limewater milky is evolved.

D.

No observable change.

7. Which of the following acids can be used to acidify silver nitrate solution for the test of halides? A.

Hydrochloric acid

B.

Dilute nitric acid

C.

Sulphuric acid

D.

Carbonic acid

8. Which of the following statements concerning hypochlorite ions are INCORRECT? A.

They are the main ingredient of the bleach.

B.

They have the oxidizing power.

C.

They turn moist blue litmus paper red.

D.

They react with with hydrochloric acid to give chlorine gas.

9. Which of the following tests can be used to distinguish between a solution containing hypochlorite ions and a solution containing sulphite ions? (1) Adding silver nitrate solution to the solutions. (2) Adding dilute hydrochloric acid to the solutions. (3) Testing the solutions with moist moist litmus paper. A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only

2


10. Which of the following substances does NOT form a precipitate with silver ions? A.

Hydrochloric acid

B.

Sulphuric acid

C.

Potassium nitrate

D.

Sodium bromide

Section 63.5 11. Which of the following statements is INCORRECT? A.

When acidified silver nitrate solution is added to sodium iodide solution, a yellow precipitate will form.

B.

When a little ammonia solution is added to iron(II) nitrate solution, a dirty green precipitate will form.

C.

When aqueous sulphur dioxide is added to acidified potassium permanganate solution, the solution will be decolorized.

D.

When but-2-ene is added to acidified potassium dichromate solution, the solution will change from orange to green.

12. Which of the following substances is odourless? A.

Ammonia solution

B.

Hydrogen sulphide

C.

Sulphur dioxide

D.

Carbon dioxdie

13. Which of following gases gives a characteristic smell? A.

Carbon dioxide

B.

Oxygen

C.

Hydrogen

D.

Sulphur dioxide

14. Which of the following statements concerning ammonia is/are correct? (1) It turns acidified potassium dichromate solution from orange to green. (2) It forms a white fume with hydrogen chloride. (3) It turns dry red litmus paper blue. A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only 3


15. Which of the following gases will turn the colour of moist litmus paper when dissolving in water? (1) Hydrogen chloride (2) Ammonia (3) Sulphur dioxide A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

16. Which of the following statements concerning sulphur dioxide are correct? (1) The reaction between aqueous sulphur dioxide and bromine water is a redox reaction. (2) Aqueous sulphur dioxide could bleach moist litmus paper. (3) It is one of the air pollutants which cause acid rain. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 63.6 17. Which of the following tests show observable colour change? (1) Test propene with bromine which is dissolved in 1,1,1-trichloromethane. (2) Test propene with acidified potassium permanganate solution. (3) Test propene with acidified potassium dichromate solution. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

4


18. Which of the following observations is INCORRECT? A.

Brick-red flame is observed when a calcium compound is heated in a Bunsen flame.

B.

A silver mirror is observed when propanone is warmed with Tollens’ reagent in a hot water bath.

C.

A white fume is observed when hydrogen chloride gas is placed near ammonia gas.

D.

A choking smell of burning sulphur is detected after adding dilute hydrochloric acid to iron(II) sulphite solution.

19. When an organic compound X is added to acidified potassium dichromate solution, a colour change is observed. Then the resultant solution is heated with ethanol in the presence of an acid, a characteristic pleasant fruity smell is detecte d. Which of the following statements are correct? (1) Compound X can be a primary alcohol. (2) Acidified potassium dichromate solution is decolorized. (3) The acid should be concentrated sulphuric acid. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

20. Which of the following test(s) is/are used to distinguish between alkanes and alkenes? (1) Reacting with bromine in shade (2) Reacting with acidified potassium dichromate solution (3) Reacting with 2,4-dinitrophenylhydrazine A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only

21. Which of the following reagents can be used to distinguish between alkenes and primary alcohols? (1) Acidified potassium permanganate solution (2) Acidified potassium dichromate solution (3) Hydrogen chloride A.

(1) only

B.

(2) only 5


C.

(1) and (3) only

D.

(2) and (3) only

22. Which of the following statements concerning Tollens’ reagents are correct? (1) It can be used to distinguish between an aldehyde and a ketone. (2) It is a solution of silver nitrate in excess ammonia solution. (3) It contains the diamminesilver(I) ion in an alkaline solution. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

23. Substance X is an organic compound. It could decolorize acidified potassium permanganate solution and turn acidified potassium dichromate solution from orange to green. Which of the following functional groups is/are more likely to be present in substance X ? (1) Hydroxyl group (2) Carbon-carbon double bond (3) Carboxyl group A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only

Section 63.7 24. The following tests were carried out to identify two unknown anions in a sample of solution and the solution was divided into three portions. Test

Observation

(1) Add acidified AgNO 3 (aq) to the

No precipitate forms

first portion (2) Add the second portion to acidified K 2 Cr 2 O 7 (aq) (3) Add a drop of solution from the

Acidified K 2 Cr 2 O 7 (aq) changed from orange to green The moist litmus paper turned white

third portion to a piece of moist litmus paper The two unknown anions should be: A.



Cl and CO 3

2

6

HKDSE Chemistry  A Modern View Part XV Analytical Chemistry 

2

B.

Br and SO 3

C.

CO 3 2 and ClO

D.

SO 3 and ClO

2



25. The following tests were carried out to identify three unknown cations in a sample of solution and the solution was divided into three portions: Test

Observation

(1) Add NH 3 (aq) to the first

Dirty green precipitate formed

portion (2) Perform flame test on the

Golden yellow flame could be observed

second portion (3) Add NaOH(aq) to the third portion and warm the mixture

A gas which turns moist red litmus paper blue was evolved

The three unknown cations should be: A.

Mg2+, Ca2+ and Al 3+

B.

Cu , Ca and Al

C.

Fe2+, Na+ and NH 4 +

D.

Fe , Na and NH 4

2+

3+

2+

+

3+

+

Section 63.8 26. Which of the following hazard warning labels are shown on the reagent bottle of benzene? (1) Oxidizing (2) Carcinogenic (3) Flammable A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Sections 64.164.2 27. Some lead(II) oxide is contaminated with a little magnesium chloride. How do we remove magnesium chloride from the mixture? A.

Add dilute acid to the mixture and then filter.

B.

Heat the mixture and then cool to room temperature.

C.

Add water to the mixture and then filter.

D.

Add water to the mixture and then cool to room temperature. 7


28. Which of the following statements concerning crystallization are correct? (1) Crystals obtained by slow cooling are more pure than those obtained quickly. (2) After filtration, we should use a large amount of distilled water to wash the crystals in order to remove any soluble impurities. (3) Crystallization is a physical method that separates a dissolved solute from its solution. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 64.3 29. Which of the following substances CANNOT be separated by distillation? A.

A mixture of proteins

B.

Crude oil fractions

C.

Oxygen and nitrogen in air

D.

Water in salt solution

Section 64.4 30. Which of the following mixtures can be separated by solvent extraction? (1) KCl(aq) and NaCl(aq) (2) Hexane and propan-2-ol (3) Ethanol and water A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only

31. Which of the following methods is the most suitable to obtain magnesium sulphate crystal from water? A.

Simple distillation

B.

Crystallization

C.

Fractional distillation

D.

Solvent extraction

8


32. Hexane and water can be separated by a separating funnel. Which of the following correctly explains why this separation method works? A.

Hexane and water have different boiling points.

B.

Hexane and water have different densities.

C.

Hexane and water have different relative molecular masses.

D.

Hexane and water do not mix.

33. After shaking the separating funnel, we should invert it and open the tap. Which of the following statements is the purpose for the above procedure? A.

To extract the desired substances more efficiently.

B.

To mix the two solvent layers by air.

C.

To get rid of the impurities.

D.

To release the pressure.

34. Which of the following statements concerning liquid-liquid extraction are correct? (1) It involves the use of a separating funnel. (2) It is used to separate two liquids which are miscible. (3) It is a physical method. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 64.5 35. Which of the following statements about chromatography is INCORRECT? A.

Alumina and silica gel are commonly packed in the vertical glass column in column chromatography.

B.

The substances with different R f values are considered as different compounds.

C.

The component substances are separated according to their different solubilities in the solvent.

D.

In paper chromatography, a pen is used for drawing the baseline.

36. There is a mixture of dye A, dye B, dye C and dye D. It is known that two of the dyes are the same. After performing paper chromatography, the following results were obtained. A red spot from dye A travelled 7 cm from the baseline. A red spot from dye B travelled 8 cm from the baseline. A yellow spot from dye C travelled 7 cm from the baseline. 9


A red spot from dye D travelled 7 cm from the baseline. The distance travelled by the solvent is 10 cm. Which of the following statements is INCORRECT? A.

The R f value of the red spot from dye A is 0.7.

B.

The R f value of the red spot from dye B is 0.8.

C.

Dye A and dye C are the same because their spots have the same R f value.

D.

Dye A and dye D are the same because their spots have the same R f value.

37. Which of the following statements about chromatography is INCORRECT? A.

Silica gel is used to be coated onto the plates for thin-layer chromatography.

B.

The R f value compares the distance travelled by a component substance to that travelled by the solvent.

C.

Every component in a mixture can be separated by using chromatography.

D.

Column chromatography can separate different solutes in a mixture for further use.

38. Which of the following methods is the most suitable to increase the concentration of ethanol in wines? A.

Crystallization

B.

Chromatography

C.

Liquid-liquid extraction

D.


39. Four coloured substances were spotted on a piece of filter paper, which was then suspended in an alcohol-water mixture. The four coloured substances include dye A, and three basic dyes red, blue and green. After some time, the following chromatogram was obtained.

A

Red (1)

Blue (2)

Green (3)

What colour does dye A contain? 10


A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

40. Which of the following statements concerning chromatography are correct? (1) Paper chromatography and thin-layer chromatography are applied for identification of different solutes in a solution. (2) Column chromatography is applied for separation of different substances in a mixture rather than for identification. (3) Chromatography is a type of physical methods. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

41. Which of the following statements concerning thin-layer chromatography are correct? (1) It is about three times faster than paper chromatography. (2) It can work with very small amounts of samples. (3) It is mainly used for the separation of organic compounds. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 64.6 42. Which of the following methods can be used for the test for purity? (1) Determination of boiling points of liquids (2) Determination of melting points of solids (3) Flame test A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

11


43. Which of the following properties shows that a solid is pure? A.

The solid is colourless.

B.

The solid melts completely.

C.

The solid does not turn the colour of dry cobalt(II) chloride paper.

D.

The solid has a sharp melting point.

44. Which of the following substances has a sharp melting point? A.

Sodium sulphate crystal

B.

Wax

C.

Gas oil

D.

Ink

45. Which of the following statements concerning the purity of a solid are correct? (1) It can be checked by determining the melting point of the solid. (2) It is only a relative idea. (3) A solid is pure if the difference between the temperature at which the solid starts to melt and the temperature at which the solid melts completely is smaller than 0.5C. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 64.7 46. Which of the following methods is the most suitable for separating crude oil? A.

Chromatography

B.

Simple distillation

C.


D.

Use of a separating funnel

47. Which of the following combinations concerning the substance and its separation method is correct? Separation method

Application

A.

Chromatographic methods

Chemicals in Chinese herbal medicines

B.

Solvent extraction

Ethanol and water

C.

Evaporation

Oil and water

D.

Filtration

Salt and sea water

12


48. Which of the following combinations concerning a separation method and its application is correct? Separation method

Application

A.

Crystallization

Getting fresh water from sea water

B.

Distillation

Getting impure common salt from sea water

C.

Evaporation

Separating pure copper(II) sulphate from its solution

D.

Filtration

Separating mud from muddy water

49. There is a mixture of propan-1-ol (b.p. = 97.2 C) and propan-2-ol (b.p. = 82.4 C). Which of the following is the best method to separate propan-1-ol from the mixture? A.

Liquid-liquid extraction

B.

Evaporation

C.

Simple distillation

D.


50. Which of the following is the best method to separate diethyl ether and water? A.

Use of a separating funnel

B.

Evaporation

C.

Simple distillation

D.


Section 65.1 51. Which of the following ions CANNOT be determined quantitatively by gravimetric analysis? (1) Ag+ +

(2) K

(3) NO 3



A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only

13


52. What is the percentage by mass of Cu in CuSO 4 • 5H 2 O? A.

63.9%

B.

39.8%

C.

35.8%

D.

25.4%

53. Find the mass of water of crystallization in 6.0 g hydrated copper(II) sulphate, CuSO 4 • 5H 2 O. A.

0.36 g

B.

0.43 g

C.

0.61 g

D.

2.17 g

54. Which of the following statements are INCORRECT? (1) The mass of precipitate should be measured immediately after taking out from the electronic oven. (2) A desiccator can be used to dry the precipitate. (3) An ordinary top-loading balance is used to measure weights with an accuracy of four or five decimal places. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

55. Which of the following statements concerning suction filtration are INCORRECT? (1) The filter paper should be wetted with distilled water. (2) The water pump can be turned off at any moment during filtration. (3) The pressure inside the filtering flask is increased when the water pump is turned on. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

14


56. In the gravimetric analysis of a compound, the following data were obtained. Mass of filter paper and precipitate after filtration = 4.5261 g Mass of filter paper before filtration = 2.5874 g Which of the following statements are correct? (1) The mass of precipitate formed in the experiment was 1.9387 g. (2) Both masses were measured by an ordinary top-loading balance. (3) The mass of precipitate formed should be found by weighing by difference. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 65.2 7. Which of the following statements concerning calcium ions are correct? (1) Its concentration indicates the hardness of water. (2) Its concentration can be determined by precipitation with oxalic acid. (3) It causes deposits in water pipes. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

58. Which of the following ions can form precipitate with calcium chloride? (1) Pb

2+

(2) C 2 O 4 (3) NO 3

2



A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

59. The barium content of a sample solution was analysed. An excess of sodium sulphate 3

was added to 500.0 cm of sample solution. The mass of barium sulphate precipitated was 3

0.046 g. What is the concentration of barium (in g dm ) in the sample solution? 3

A.

0.027 g dm

B.

0.046 g dm3

C.

0.054 g dm

D.

0.092 g dm

3

3

15


60. Which of the following reactions can be applied for gravimetric analysis? (1) The reaction between copper(II) sulphate solution and excess ammonia solution. (2) The reaction between barium hydroxide solution and sodium sulphate solution. (3) The reaction between calcium chloride solution and lead(II) nitrate solution. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

61. 2.560 g of impure copper(II) sulphate sample was dissolved in water and precipitated with excess sodium hydroxide solution. If 1.245 g copper(II) hydroxide was obtained, what is the percentage of copper(II) sulphate in the impure sample? A.

39.90%

B.

48.21%

C.

79.80%

D.

96.42%

Sections 65.365.4 62. Which of the following statements concerning the apparatus routinely used for titration is INCORRECT? A.

Pipette is used to transfer a fixed amount of a solution accurately.

B.

Measuring cylinder is used to deliver variable volumes of a solution accurately.

C.

Electronic balance is used for fast and accurate weighing.

D.

Volumetric flask is used to make up a certain solution to a specific volume accurately.

63. Which of the following statements about Mohr’s method is INCORRECT? A.

The pH of the reaction mixture should not be too high to prevent the formation of undesirable precipitates.

B.

The pH of the reaction mixture should not be too low to prevent the conversion of chromate ions to dichromate ions.

C.

This method is used to determine the concentration of chloride ions in a water sample.

D.

A bluish-green precipitate can be observed at the end point of the titration.

16


64. Which of the following are used to detect the end point of a precipitation titration? (1) Conductivity of the reaction mixture (2) Mass of the precipitates formed (3) A suitable indicator A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3) 3

65. What is the molarity of a 500.0 cm solution containing 2.65 g of sodium carbonate? A.

0.025 M

B.

0.050 M

C.

0.075 M

D.

1.000 M

66. Which of the following statements concerning Mohr’s method are correct? (1) It is used to determine the chloride ion concentration of a water sample by precipitation titration against a silver nitrate solution. (2) The indicator used in this method is potassium dichromate. (3) It should be carried out in pH 6.59. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3) 3

67. A 500.0 cm potassium chloride solution was prepared by dissolving potassium chloride in distilled water. 25.0 cm3 of the solution was titrated with 0.300 M silver nitrate 3

solution. 28.90 cm of silver nitrate solution was required to reach the end point in the titration. What is the number of moles of potassium chloride present in the 500.0 cm

3

solution? A.

0.009 mol

B.

0.029 mol

C.

0.173 mol

D.

8.670 mol

17


68. Which of the following is the suitable pH for Mohr’s method? A.

pH < 2

B.

pH = 36.5

C.

pH = 6.59

D.

pH  10

69. Which of the following statements are correct? (1) A specific volume of analyte is transferred into a conical flask for titration by a pipette. (2) The titrant is run from the burette into the conical flask. (3) Precipitation titration is a type of volumetric analysis. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

70. Which of the following statements concerning Mohr’s method are correct? (1) It is a kind of precipitation titration. (2) Potassium dichromate is used as the indicator. (3) It should be carried out in pH 6.59. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 65.5 71. Which of the following is used as an indicator for the titration between iodine and sodium thiosulphate solution? A.

Potassium chromate

B.

Methyl orange

C.

Phenolphthalein

D.

Starch solution

18


72. Which of the following statements concerning the determination of water quality are correct? (1) It applies permanganate index to show the water quality. (2) The smaller the permanganate index, the better is the quality of water. (3) It involves redox titrations. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

73. Which of the following statements concerning permanganate index is INCORRECT? A.

3

Permanganate index should not exceed 4 mg dm according to the national standard.

B.

The determination of permanganate index involves a redox titration.

C.

Excess sodium oxalate solution is added to remove any residual potassium permanganate.

D.

An indicator is required in the titration.

Section 66.1 74. Which of the following are the advantages of using instrumental analytical methods over conventional analytical methods? (1) Less human error is involved. (2) Less harmful chemicals and apparatus are involved. (3) Less sample is used. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

Section 66.2 75. Which of the following chemical solutions can be quantitatively analysed by a colorimeter? (1) Potassium permanganate solution (2) Copper(II) sulphate solution (3) Sodium chloride solution A.

(1) and (2) only

B.

(1) and (3) only 19


C.

(2) and (3) only

D.

(1), (2) and (3)

76. The following diagram shows a calibration curve of a blue food dye. If a sample containing unknown concentration of blue dye has an absorbance of 0.56. What is the concentration of the blue dye?

e c n a b r o s b A

3

Concentration of blue dye (g dm ) 3

A.

6.0 g dm

B.

6.5 g dm3

C.

7.0 g dm

D.

7.5 g dm

3 3

Section 66.3 77. Which of the following absorption bands must be observed in IR spectrum of propene? 1

A.

A strong absorption peak between 16101680 cm .

B.

A strong and broad absorption band at around 3200 cm 1.

C.


D.


1 1

20


78. What is the name of compound that gives the following infrared spectrum?

) % ( e c n a t t i m s n a r T

Wavenumber (cm1) A.

Butanoic acid

B.

Butane

C.

Butan-1-ol

D.

Butan-2-one

79. Which of the following information obtained from the infrared spectrum can be used to distinguish between ethanoic acid and ethanol? 1

A.

The presence of broad absorption peaks at 32303670 cm .

B.

The absence of broad absorption peaks at 32303670 cm .

C.

The presence of absorption peaks at 16801750 cm1.

D.

The presence of absorption peaks at 27202820 cm .

1

1

21




1

Wavenumber (cm ) A.

Propene

B.

Butanoic acid

C.

Methyl ethanoate

D.

Butan-1-ol



Wavenumber (cm1)

A.

Pent-1-ene

B.

Propan-2-one

C.

Propanenitrile

D.

Propan-1-ol

22


82. Which of the following statements concerning vibrational frequency are correct? (1) It is unique for each type of bond. (2) Weaker bonds vibrate at higher frequencies than stronger bonds. (3) Lighter atoms usually vibrate at higher frequencies than heavier atoms. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

83. Which of the following statements concerning infrared spectroscopy are correct? (1) Wavenumber is directly proportional to frequency. (2) C N bond vibrates at a higher frequency than C=C bond. 1

(3) A strong and broad absorption peak at around 3300 cm corresponds to the absorption of O H bond in alcohols or carboxylic acids. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

84. Which of the following absorption peaks is observed in the IR spectrum of phenol? 1

A.

A strong peak at around 1700 cm

B.


C.

A strong peak at around 2250 cm 1

D.


1

1

85. Which of the following is the correct descending order of bond strength? A.

C=C > C=O > C C > C N

B.

C=C > C C > C=O > C N

C.

C N > C=O > C C > C=C

D.

C N > C C > C=O > C=C

23


Section 66.4 86. Which of the following statements concerning mass spectrometry is correct? A.

In the mass spectrum, the y-axis is the relative abundance of positive ions generated while the x-axis is mass.

B.

The magnetic field in the mass spectrometer is used to accelerate the ions.

C.

The positive ions in the mass spectrometer are generated by bombarding the gaseous sample with fast moving electrons.

D.

Ions with a higher mass-to-charge ratio are deflected more than those with a lower mass-to-charge ratio.

87. Which of the following statements concerning mass spectrometry is INCORRECT? A.

It can distinguish between a pair of structural isomers.

B.

The sample analysed by the mass spectrometry must be pure.

C.

The mass spectrometry has a detection limit.

D.

The base peak must be the peak corresponding to the molecular ion.

88. Referring to the mass spectrum of chloromethane, what is the peak height ratio of 35

+

37

+

CH 3 Cl : CH 3 Cl ? A.

2:1

B.

1:2

C.

1:3

D.

3:1

89. Which of the following peaks can be observed in the mass spectrum of hexane? (1) The peak at m/e = 43 (2) The peak at m/e = 57 (3) The peak at m/e = 86 A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

90. Which of the following statements concerning the molecular ion of a compound in a mass spectrum are correct? (1) It gives the highest value of m/e ratio. (2) Its relative abundance must be the highest. (3) The m/e ratio of the molecular ion shows the relative molecular mass of the compound. 24


A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

91. Which of the following statements concerning base peak is correct? A.

It is the peak with the highest mass-to-charge ratio.

B.

It must be the molecular ion peak.

C.

It is the peak with the highest relative abundance.

D.

It is the peak contributed by the isotope of an element of the compound.

92. The mass spectrum of pentan-3-one is shown below. Which of the following combinations are correct?

) % ( e c n a d n u b a e v i t a l e R

m/e

Ion

m/e ratio +

(1)

CH 3 CH 2 COCH 2 CH 3

(2)

CH 3 CH 2 CO+

57

(3)

CH 3 CH 2 +

29

A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

86

25


93. Which of the following statements are correct? (1) Colorimetry determines the concentration of a coloured chemical solution by measuring the amount of light it absorbs. (2) Infrared spectroscopy identifies particular functional groups in molecules. (3) Mass spectroscopy identifies the structures of unknown substances. A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

94. Which of the following analytical instruments CANNOT be used to distinguish between a pair of enantiomers? (1) A colorimeter (2) An infrared spectrometer (3) A mass spectrometer A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

95. The concentration of copper(II) sulphate solution can be determined by (1) an infrared spectrometer. (2) a colorimeter. (3) a mass spectrometer. A.

(1) only

B.

(2) only

C.

(1) and (3) only

D.

(2) and (3) only

96. Which of the following information can be obtained from the mass spectrum? (1) The empirical formula of a compound (2) The relative molecular mass of a compound (3) The structure of a compound A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

26


Section 66.5 97. Which of the following analytical methods are necessary to determine the structural formula of an unknown organic compound? (1) Colorimetry (2) Infrared spectroscopy (3) Mass spectroscopy A.

(1) and (2) only

B.

(1) and (3) only

C.

(2) and (3) only

D.

(1), (2) and (3)

27

Analytical Chemistry Mc Questions

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