Form 2 Chapter 5

Form 2 Science Chapter 5

FORM 2 CHAPTER 5 WATER AND SOLUTION

1. Diagram 1 shows the apparatus used in the electrolysis of water.

(a) Suggest one example of substance Z.

…………………………………………………………………………………………………….

[1 mark]

(b) Which of the two carbon rods function as the negative electrode?

………………………………………………………………………………………………………

[1 mark]

(c) When the circuit is switched on, some gas is collected in each test tube.

(i) What is the gas collected in test tube P?

…………………………………………………………………………………………………..

[1 mark]

(ii) Suggest one way to identify the gas collected in test tube P.

…………………………………………………………………………………………………

[1 mark]

JPN Pahang 2009 87

Test tube P

Water + Substance Z

Diagram 1

Test tube Q

Carbon rod X Carbon rod Y


(iii) What is the gas collected in test tube Q?

……………………………………………………………………………………………….

[1 mark]

(iv) Suggest a way to identify the gas collected in test tube Q .

………………………………………………………………………………………………

[1 mark]

(d) State the expected ratio of the volume of the gas collected in test tube Q to the volume of the gas collected in test tube P.

……………………. ………………………………………………………………………………..

[1 mark]

JPN Pahang 2009 88


2. Diagram 2 shows an activity conducted to determine the freezing point and the boiling point of water.

(a) Why is salt added to the ice cubes in A?

………………………………………………………………………………………………………

[1 mark]

(b) What is the function of the glass tube in B?

………………………………………………………………………………………………………

[1 mark]

(c) State the temperature of water in A when it begins to freeze.

………………………………………………………………………………………………………

[1 mark]

(d) State the temperature of water in B when it begins to boil.

………………………………………………………………………………………………………

[1 mark]

(e) What is the change in the state of matter when water

(i) freezes: …………………………………………………………………………………….

(ii) boils: ……………………………………………………………………………………………[2 marks]

JPN Pahang 2009 89

Diagram 2


(f) What happens to the motion of water molecules when water

(i) freezes: …………………………………………………………………………………………

(ii) boils:………….…………………………………………………………………………………

[2 marks]

JPN Pahang 2009 90


3. Diagram 3 shows an experiment to study the effect of humidity on evaporation.

(a) State the variables in the experiment.

(i) Manipulated variable: ………………………………………………………………………..

(ii) Responding variable: ……………………………………………………………………….

(iii) Constant variable: ……………………………………………………………………………

[3 marks]

(b) What is the function of the anhydrous calcium chloride?

………………………………………………………………………………………………………

[1 mark]

(c) Name another chemical substance that can be used to replace the anhydrous calcium chloride.

………………………….………………………………………………………………………….

[1 mark]

(d) Why is the beaker containing water placed in the bell jar P?

………………………………………………………………………………………………………

[1 mark] (e) What would be observed in bell jar P and bell jar Q after one hour? Why?

………………………………………………………………………………………………………

………………………………………………………………………………………………………

[2 marks]

JPN Pahang 2009 91

Diagram 3


(f) State two other factors that influence the rate of evaporation.

(i) ………………………………………………………………………………………………....

(ii) …………………………………………………………………………………………………..

[2 marks]

JPN Pahang 2009 92


4. Diagram 4.1 shows pictures of substances P, Q, R and S.Table 4.2 shows the pH of the substances P, Q, R and S when tested with universal indicator

Substance P Q R S

pH 9 3 8 2

Table 4.2

(a) Based on your observation on Diagram 4.1 and Table 4.2 state one property of substances P, Q, R and S .

P: …………………………………………………………………………………………………..

Q: …………………………………………………………………………………………………..

R: …………………………………………………………………………………………………..

S: …………………………………………………………………………..…………………….

[4 marks]

JPN Pahang 2009 93

Diagram 4.1

Milk of magnesia

P

Orange

Q

Toothpaste

R

Vinegar

S


(b) Classify the substances P, Q, R and S into two groups based on their common properties.

Write the names of the substances belonging to each group

[4 marks]

JPN Pahang 2009 94

Common property

P, Q, R, and S

Names of substances


5. Diagram 5.1 shows the reaction between dilute hydrochloric acid and sodium hydroxide.

The results of the activity are recorded in Table 5.2

Change in colour of universal indicator

Initial FinalPurple M

pH value 9 7

Table 5.2

(a)(i) State the colour of M.

…………………………………………………………………………………………………….

[1 mark]

(ii) Name the process that causes this change in colour. …………………………………………………………………………………………………….

[1 mark]

(iii) Complete the word equation that shows the reaction.

[2 marks]

JPN Pahang 2009 95

Dilute hydrochloric acid

Sodium hydroxide solution + universal indicator

Diagram 5.1

Hydrochloric acid + Sodium hydroxide +


(b) Diagram 5.2 shows several substances with different pH values.

(i) Based on Diagram 5.2, complete the table below by giving one example for each group of substances.

Acidic Alkaline

[2 marks]

(ii) What is the pH value of distilled water?

…………………………………………………………………………………………………….

[1 mark]

(iii) Why do we use toothpaste to brush our teeth? …………………………………………………………………………………………………….

[1 mark]

JPN Pahang 2009 96

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

lemon apple tomato toothpaste soap

Milk of magnesia

Diagram 5.2

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Form 2 Chapter 5