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.
