F2 IS 2nd term QZ 06 (10.3) ans

QZ 06: 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

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.

Lemon (OR any other reasonable acidic food)

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

The indicator turns blue or violet.