ASSIGNMENT BOOK Unit 10 Part 2 Part 2 Integrated Exercises (Unit Test) A. True or False (Total 20 marks; 2 marks each) Study the following statements. Put a ‘ T ’ in the box against a correct statement and a ‘F’ against an incorrect statement. 1.The acids in lemons and apples are safe to take in. F T 2.Sodium chloride is a commonly used alkali in the school laboratory.

ASSIGNMENT BOOK Unit 10 Part 2 3.Blue litmus paper is used to test for acids. T F F T 5.Acids with a higher pH value are more acidic. 4.Acids have a pH of 1 and alkalis have a pH of When dilute hydrochloric acid is added to marble, the gas formed can turn lime water milky.

ASSIGNMENT BOOK Unit 10 Part 2 T F F T 10.We can neutralise the sting from a wasp by vinegar solution. 7.If you get acids or alkalis on your skin, you should wash the affected area with slow running water for at least ten minutes. 8.The pH value of rainwater is 7. 9.Carbon dioxide is the main air pollutant that causes acid rain.

ASSIGNMENT BOOK Unit 10 Part 2 B.Multiple Choice Questions (Total 30 marks; 2 marks each) Write the correct answer to each question in the box provided. 1. Which of the following acids are present in lemons? (1)citric acid (2)ascorbic acid (3)ethanoic acid A.(1) and (2) only B.(1) and (3) only C.(2) and (3) only D.(1), (2) and (3) A

ASSIGNMENT BOOK Unit 10 Part 2 2. A substance which changes colour when it is mixed with an acid or an alkali is called A.a table salt. B.a detergent. C.caustic soda. D.an indicator. D

ASSIGNMENT BOOK Unit 10 Part 2 3. When a piece of red litmus paper is dipped into toothpaste, it will A.remain red. B.turn blue. C.become colourless. D.turn purple. B

ASSIGNMENT BOOK Unit 10 Part 2 C 4.Which of the following is the correct order of the reactivity of metals? A.aluminium, magnesium, copper, iron, zinc B.magnesium, aluminium, iron, copper, zinc C.magnesium, aluminium, zinc, iron, copper D.copper, zinc, magnesium, aluminium, iron Most reactive Least reactive

ASSIGNMENT BOOK Unit 10 Part 2 5.Acid + X salt + water In the above equation, solution X is A.an indicator. B.an alkali. C.distilled water. D.a salt. B

ASSIGNMENT BOOK Unit 10 Part 2 6.The following table shows four solutions and their pH values. A.W. B.X. C.Y. D.Z. A Hydrogen will be given off when a magnesium ribbon is added to solution ZYXW Solution pH value

ASSIGNMENT BOOK Unit 10 Part 2 7.One is advised not to use iron utensils for cooking vinegar because A.iron will be corroded by vinegar. B.iron will melt immediately. C.iron will combine with vinegar to form a toxic substance. D.iron will cause vinegar to lose its sour taste. A

ASSIGNMENT BOOK Unit 10 Part 2 8.An experiment should be carried out inside a fume cupboard if the experiment A.involves a strong acid. B.gives out a lot of heat. C.gives out a harmful gas. D.requires strong heating. C

ASSIGNMENT BOOK Unit 10 Part 2 9.Which of the following is most likely the pH of natural rainwater? A.2 B.4 C.6 D.8 C

ASSIGNMENT BOOK Unit 10 Part 2 D 10.Which of the following will NOT reduce the formation of acid rain? A.planting more trees B.cutting down the number of motor cars C.using less fossil fuel D.neutralising the acidic gas released from factories

ASSIGNMENT BOOK Unit 10 Part 2 11.Which of the following statements about acids is INCORRECT? A.All acids are damaging to our skin. B.We can use pH paper to find out how acidic an acid is. C.The digestive juice in the stomach contains hydrochloric acid. D.Tooth decay is caused by an acid produced by mouth bacteria. A

ASSIGNMENT BOOK Unit 10 Part 2 12.A student used dilute sodium hydroxide solution to neutralise dilute hydrochloric acid. However, he/she added too much sodium hydroxide solution. The pH of the resulting solution was most probably A.2. B.5. C.7. D.12. D

ASSIGNMENT BOOK Unit 10 Part 2 13.Which of the following about an oven cleaner is correct? A.It contains a strong alkali, ammonia. B.It can be neutralised by distilled water. C.It can remove grease on the ovens. D.It is corrosive. D

ASSIGNMENT BOOK Unit 10 Part 2 14.Which of the following acids is commonly used in pickling? A.hydrochloric acid B.ethanoic acid C.sodium hydroxide D.ammonia B

ASSIGNMENT BOOK Unit 10 Part 2 15.Acids can be used to preserve food because they A.make the food sour. B.can kill bacteria. C.react with food to form hydrogen. D.neutralise the alkali in food. B

ASSIGNMENT BOOK Unit 10 Part 2 1.The pH values of five different substances are shown in the table below. These pH values are obtained from a pH meter. C.Question (Total 50 marks) PQRST Substance pH value

ASSIGNMENT BOOK Unit 10 Part 2 (a)Which substance could be(4 marks) (i)pure water? _________ (iii)vinegar? ________ (ii)liquid soap? _________ (iv)lime water? ______ (b)Which TWO of the substances would you expect to be the most corrosive? (4 marks) Q and R (c)What are the advantages of using a pH meter over pH paper?(4 marks) More accurate results can be obtained. Clear experimental results can be obtained even for coloured substances. S T R Q

ASSIGNMENT BOOK Unit 10 Part 2 2.Tom is diluting a strong acid. water strong acid

ASSIGNMENT BOOK Unit 10 Part 2 He should wear gloves and safety spectacles. He should add strong acid slowly to a large amount of water. He should stir the solution continuously throughout the diluting procedure. He should carry out the process inside a fume cupboard. What is wrong with Tom's procedures? What safety precautions should he take? (12 marks)

ASSIGNMENT BOOK Unit 10 Part 2 3.The diagram on the right shows the conditions of tooth decay. (a)What type of substance produced by the mouth bacteria causes tooth decay? (2 marks) acid

ASSIGNMENT BOOK Unit 10 Part 2 Alkaline Saliva is alkaline which can neutralise the acids produced by the bacteria in the mouth. (b)Chewing can stimulate the production of saliva in the mouth. This can help prevent tooth decay. (i)Is saliva acidic or alkaline?(2 marks) (ii)Explain why the production of saliva in the mouth can help prevent tooth decay. (4 marks)

ASSIGNMENT BOOK Unit 10 Part 2 It neutralises the acid which is produced by the mouth bacteria. (c)Explain why toothpastes usually have a pH of about 8.(2 marks)

ASSIGNMENT BOOK Unit 10 Part 2 4.Drain cleaners contain a strong alkali. A corrosive warning sign is usually found on the container.

ASSIGNMENT BOOK Unit 10 Part 2 sodium hydroxide / caustic soda He / She should wear safety spectacles to protect his / her eyes. He / She should wear gloves to protect his / her hands. (a)Name the strong alkali usually found in drain cleaners.(2 mark) (b)What safety measures should be taken when a person is using the cleaner?(6 marks)

ASSIGNMENT BOOK Unit 10 Part 2 5.Some reagent bottles in the laboratory have their labels missing. They are known to contain dilute sulphuric acid, distilled water, vinegar and dilute sodium hydroxide solution. How can you identify the contents of each bottle by using pH paper? (8 marks)

ASSIGNMENT BOOK Unit 10 Part 2 Add a little of the content of each bottle to four different test tubes. Use pH paper to check its pH value: dilute sulphuric acid pH 1 vinegar pH 3 distilled water pH 7 dilute sodium hydroxide solution pH 12-14