true or false review
TRANSCRIPT
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