true or false review

True or False Review

Common Acids and Alkalis

1. Strong acids can react with other substances to

produce more acid.

2. Only acids are corrosive.

3. Cobalt chloride paper can be used to test for

acids and alkalis.

4. A hairstylist uses an acid to soften the hair so that it can take the shape

of the hair curlers.

5. The acids found in foods and drinks are

weak acids. Weak acids are quite safe to take in.

6. Only strong alkalis are used as household cleansing liquids.

7. Red litmus paper is used to test for acids

and blue litmus paper is used to test for alkalis.

8. Litmus paper is also called pH paper.

9. Toothpaste contains an acid which kills

bacteria in the mouth.

10. We use a blue litmus paper to test whether a

solution is alkaline or not.

11. Universal indicator is a mixture of dyes.

12. Corrosive hazard warning labels should be put on the bottles of some household

cleansers, e.g. oven cleanser and toilet cleanser.

13. Indicators are dyes which change colour

when placed in an acid or an alkali.

14. Acids can be found in milk products like cheese and yogurt.

15. The degree of acidity or alkalinity can be expressed

by its pH value. Acids have a pH value less than 7 while

alkalis have a pH value greater than 7.

16. The degree of acidity and alkalinity can be expressed by its pH.

17. Acids have a pH value less than 7 while alkalis have a pH value

greater than 7.

18. Alkalis are not corrosive.

19. Acids can be added to food and drinks to improve the tastes.

20. Litmus paper can be used to indicate

whether a solution is acidic or alkaline.

21. Litmus paper can be used to indicate how

strong or how weak an acid or an alkali is.

22. All acids have a sour taste.

23. All alkalis feel soapy and have a bitter taste.

24. The soft drink “Cream Soda” contains

caustic soda.

25. pH paper turns orange or red when

placed in acidic solution.

26. pH paper turns yellow or green when

placed in neutral or nearly neutral solutions.

27. pH paper turns purple or brown when placed in a neutral or

nearly neutral solutions.

28. The digestive juice in our stomach is a weak

acid so it does not harm us.

29. Apples are acidic.

30. Alkalinity increases when pH increases.

31. All metals react with dilute acids to give off

hydrogen.

32. Hydrogen burns in air to produce a “pop”

sound.

33. All metals react with alkalis to form carbon

dioxide.

34. An aluminum pot is suitable to contain

tomato soup.

35. Acids can corrode marbles surfaces.

36. Acid rain buildings made of marbles,

limestone and cement.

37. If you get acids on your skin, you should

neutralise them by adding suitable amount of alkalis.

38. For safety reason, household cleansers are

always sold in diluted solution.

39. If we want to dilute a concentrated alkali,

we should add water to it carefully.

40. When diluting a strong acid, the best way to do this is to add water

to the strong acid and stir.

41. Reactions involving strong acids and strong alkalis usually give out a

lot of heat.

42. When there is an accident involving acids and alkalis, we must neutralise the acid or the

alkalis with chemicals immediately.

43. When diluting a strong alkali, we should wear protective gloves

and eyeglasses.

44. The pH of natural rainwater is around 7.

45. Acid rain speeds up the release of metals from minerals in soil. These metals are important for

plant growth.

46. Acid rain damages the leaves of trees, affecting the process of photosynthesis.

47. In order to improve air quality, the Government will replace all

diesel vehicles by liquefied petroleum gas vehicles.

48. The tap water in Hong Kong is always

neutral.

49. The pH value of acid rain can be as low as 3.

50. Sulphur dioxide affects the growth of fish

in rivers.

51. Acid rain is caused by acidic gases such as

nitrogen dioxide and sulphur dioxide in the air.

52. Rainwater is neutral.

53. Acid rain is diluted in lakes and rivers, so it does not harm fish in fish ponds

and lakes.

54. Fish in lakes die when the water is so acidic that

the pH is above 6.

55. One of the main causes of acid rain is emission of nitrogen oxides from vehicles.

56. The process of adding water to an acidic or

alkaline solution is called neutralisation.

57. The only product formed after

neutralisation is water.

58. Adding Sodium Chloride to hydrochloric

acid is an example of neutralization.

59. We can detect the product of neutralization

by tasting it.

60. Hydrochloric acid can be used to preserve food

because it kills germs.

61. All cleansing agents contain both acids and

alkalis.

62. Antacids contain a strong alkali which

neutralises the strong acid produced by the stomach.

63. All insect bites contain alkali.

64. Toothpastes contain a weak alkali which

neutralises the acid produced by the bacteria.

65. The chemical waste from school laboratories

will be collected by licensed collectors for disposal.

66. The industrial wastes containing acids and alkalis,

if discharged without treatment into the sea or

streams, will cause corrosion of metal pipes and ships.

67. Concentrated hydrochloric acid can

dissolve glass and therefore it must be stored in lead,

steel or plastic containers.

68. Acids/Alkalis can act as preservatives.

69. Lime can be added to soil to reduce the

acidity.

70. When an alkali is neutralised by an acid, salt

and water are formed.

71. When some water is added to an acid, the

amount of alkali needed to neutralise it increases.

72. Pickling is a method used to preserve food.

73. Sodium chloride is a strong alkali.

74. Strong alkalis can break down fat and are used to remove grease.

75. Antacids contain a weak alkali that can neutralise the strong acid produced by the

stomach.

76. Acids and alkalis are chemical opposites.

77. Oven cleaners are strongly acidic so they can corrode the stains on the

oven away.

78. Ethanoic acid is used to preserve food because

acids can kill bacteria.

79. “Pickling” means adding salt to preserve

food.

80. An apple turns brown after it is cut open. It is because the iron in the

apple rusts.

81. When you eat too much, your stomach will

produce more acid.

True or False Answers

Common Acids and Alkalis

1. Strong acids can react with other substances to

produce more acid.

True

2. Only acids are corrosive.

False

3. Cobalt chloride paper can be used to test for

acids and alkalis.

False

4. A hair stylist uses an acid to soften the hair so that it can take the shape

of the hair curlers.

False

5. The acids found in foods and drinks are

weak acids. Weak acids are quite safe to take in.

False

6. Only strong alkalis are used as household cleansing liquids.

False

7. Red litmus paper is used to test for acids and blue litmus

paper is used to test for alkalis.

False

8. Litmus paper is also called pH paper.

False

9. Toothpaste contains an acid which kills

bacteria in the mouth.

False

10. We use a blue litmus paper to test whether a

solution is alkaline or not.False

11. Universal indicator is a mixture of dyes.

True

12. Corrosive hazard warning labels should be put on the bottles of some household cleansers, e.g. oven cleanser and toilet cleanser.

True

13. Indicators are dyes which change colour when placed in

an acid or an alkali.

True

14. Acids can be found in milk products like cheese and

yogurt.

True

15. The degree of acidity or alkalinity can be expressed by its pH value. Acids have a pH value less than 7 while alkalis

have a pH value greater than 7.

True

16. The degree of acidity and alkalinity can be expressed by its pH.

True

17. Acids have a pH value less than 7 while alkalis have

a pH value greater than 7.

True

18. Alkalis are not corrosive.

False

19. Acids can be added to food and drinks to improve the tastes.

True

20. Litmus paper can be used to indicate whether a

solution is acidic or alkaline.

True

21. Litmus paper can be used to indicate how strong or how

weak an acid or an alkali is.

True

22. All acids have a sour taste.

True

23. All alkalis feel soapy and have a bitter taste.

True

24. The soft drink “Cream Soda” contains caustic

soda.

False

25. pH paper turns orange or red when placed in

acidic solutions.

True

26. pH paper turns yellow or green when placed in neutral or nearly neutral

solutions.

True

27. pH paper turns purple or brown when placed in a neutral or nearly neutral

solutions.

False

28. The digestive juice in our stomach is a weak acid so it

does not harm us.

False

29. Apples are acidic.

True

30. Alkalinity increases when pH increases.

True

31. All metals react with dilute acids to give off

hydrogen.

False

32. Hydrogen burns in air to produce a “pop”

sound.

True

33. All metals react with alkalis to form carbon

dioxide.

False

34. An aluminum pot is suitable to contain tomato

soup.

True

35. Acids can corrode marbles surfaces.

True

36. Acid rain attacks buildings made of marbles,

limestone and cement.

True

37. If you get acids on your skin, you should neutralise

them by adding suitable amount of alkalis.

False

38. For safety reason, household cleansers are

always sold in diluted solution.

False

39. If we want to dilute a concentrated alkali, we should add water to it

carefully.

False

40. When diluting a strong acid, the best way to do this is to add water to the strong acid

and stir.

False

41. Reactions involving strong acids and strong alkalis

usually give out a lot of heat.

True

42. When there is an accident involving acids and alkalis, we must

neutralise the acid or the alkalis with chemicals immediately.

False

43. When diluting a strong alkali, we should wear protective gloves and

eyeglasses.

True

44. The pH of natural rainwater is around 7.

False

45. Acid rain speeds up the release of metals from minerals in soil. These metals are

important for plant growth.

False

46. Acid rain damages the leaves of trees, affecting the process of photosynthesis.

True

47. In order to improve air quality, the Government will replace all diesel vehicles

by liquefied petroleum gas vehicles.

False

48. The tap water in Hong Kong is always neutral.

False

49. The pH value of acid rain can be as low as 3.

True

50. Sulphur dioxide affects the growth of fish in rivers.

True

51. Acid rain is caused by acidic gases such as nitrogen dioxide and sulphur dioxide in the air.

True

52. Rainwater is neutral.

False

53. Acid rain is diluted in lakes and rivers, so it does not harm

fish in fish ponds and lakes.

False

54. Fish in lakes die when the water is so acidic that the pH is

above 6.

False

55. One of the main causes of acid rain is emission of

nitrogen oxides from vehicles.

True

56. The process of adding water to an acidic or alkaline solution is

called neutralisation.

False

57. The only product formed after neutralisation is water.

False

58. Adding Sodium Chloride to hydrochloric acid is an

example of neutralization.

False

59. We can detect the product of neutralization by tasting it.

False

60. Hydrochloric acid can be used to preserve food because

it kills germs.

False

61. All cleansing agents contain both acids and

alkalis.

False

62. Antacids contain a strong alkali which neutralises the strong acid produced by the

stomach.

False

63. All insect bites contain alkali.

False

64. Toothpastes contain a weak alkali which neutralises the

acid produced by the bacteria.

True

65. The chemical waste from school laboratories will be

collected by licensed collectors for disposal.

True

66. The industrial wastes containing acids and alkalis, if discharged without treatment

into the sea or streams, will cause corrosion of metal pipes

and ships.

True

67. Concentrated hydrochloric acid can dissolve glass and

therefore it must be stored in lead, steel or plastic containers.

False

68. Acids/Alkalis can act as preservatives.

True

69. Lime can be added to soil to reduce the acidity.

True

70. When an alkali is neutralised by an acid, salt

and water are formed.True

71. When some water is added to an acid, the amount of alkali

needed to neutralise it increases.

False

72. Pickling is a method used to preserve food.

True

73. Sodium chloride is a strong alkali.

False

74. Strong alkalis can break down fat and are used to remove grease.

True

75. Antacids contain a weak alkali that can neutralise the strong

acid produced by the stomach.

True

76. Acids and alkalis are chemical opposites.

True

77. Oven cleaners are strongly acidic so they can corrode the

stains on the oven away.

False

78. Ethanoic acid is used to preserve food because acids can kill bacteria.

True

79. “Pickling” means adding salt to preserve

food.

False

80. An apple turns brown after it is cut open. It is because the

iron in the apple rusts.

False

81. When you eat too much, your stomach will

produce more acid.

True