F2 IS 2nd Term QZ 06: 10.3 anwers

10.3

Word Translation (11 marks)

i    Write down the English terms of the following Chinese terms:

	Chinese term	English term
1	天然的	Natural
2	指示劑	Indicator
3	石蕊試紙 / 溶液	Litmus paper / solution
4	酸性的 / 酸度	Acidic / acidity
5	鹼性的 / 鹼度	Alkaline / alkalinity
6	中性的	Neutral
7	通用指示劑	Universal indicator
8	程度	Degree
9	pH試紙	pH paper
10	pH值	pH value
11	pH標度	pH scale

Multiple Choice (5 marks)

Circle the letter of the best answer for each question.

1.       The following table shows the colours of some plant extracts in acids and alkalis.

Plant extract	Colour in acids	Colour in alkalis
W	Red	Blue
X	Purple	Red
Y	Pink	Yellow
Z	Yellow	Yellow

Which of the above plant extracts CANNOT be used as an acid-alkali indicator?

A.   Plant extract W        B.    Plant extract X                C.    Plant extract Y         D.    Plant extract Z

2.       Peter has tested three solutions in the laboratory. His results are shown below.

Solution P: It does not turn red litmus paper blue.

Solution Q: It turns blue litmus paper red.

Solution R: It does not change the colours of both red and blue litmus paper.

Which of the following statements must be correct?

A.   Solution R is distilled water.                           B.    Solution P is more acidic than solution R.

C.   Solution Q is more acidic than solution P.     D.    Solution Q is more acidic than solution R.

3.       Which of the following can we use to test whether orange juice or lemon juice is more acidic?

(I)   pH paper                         (II)   Litmus paper                           (III) Universal indicator solution

A.   (I) only

B.   (I) and (II) only

C.   (I) and (III) only

D.   (II) and (III) only

  

4.       Which of the following substances is the most acidic?

	Substance	pH value
A.	P	-1
B.	Q	0
C.	R	14
D.	S	15

5.       Which of the following substances is the most alkaline?

A.   Fresh milk                                                               B.    Lime water

C.   Baking soda solution                                              D.    Dilute sodium hydroxide

Fill in the Blanks (13 marks)

1        Some deeply coloured plants show different colours in acids and alkalis. They can be used to make

(1)   natural acid-alkali (2) indicator.

2        If something turns blue (3) litmus paper red, it is said to be (4) acidic.

3        Distilled water does not change the colours of both blue and red litmus paper. It is said to be

(5) neutral.

4    (6) Alkaline substances turn red litmus paper blue but do not change the colour of blue litmus paper.

5    (7) Universal indicator can show the degree of acidity or (8)_alkalinity of a substance. Its paper form is called (9) pH paper.

6     The scale for measuring acidity or alkalinity is called (10) pH scale. An acid has a

(11) pH value smaller than 7 while that of an alkali is greater than 7.

5     The lower the pH value, the more (12) acidic a substance is;

       The higher the pH value, the more (13) alkaline it is.

Challenging Questions (Bonus 2 marks)

1.      State a common food which as a pH value lowers than 7.               Any food which is acidic

2.      If sodium hydroxide is mixed with universal indicator, what happens?

The colour of the universal indicator changes to blue or violet.