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Chapter 1 Introduction to Chemistry

Paper 1Answer all the questions.

Questions 1-5 are based on the fi gure below.

1

The fi gure shows the apparatus set-up of an experiment to investigate the effect of

concentration of hydrochloric acid on the rate of reaction. 5 g of marble chips are added to 50 cm3 of 1.0 mol dm–3 hydrochloric acid. The balance reading is taken immediately after the marble chips are added and again at one-minute of intervals until the reaction is completed. The experiment is repeated by changing the concentration of hydrochloric acid to 0.5 mol dm–3.

The fi xed variables in this experiment are I the concentration of hydrochloric acid II the mass of marble chips used III the volume of hydrochloric acid IV the interval time taken for the reactants to react completely A I,II and III only B I, II and IV only C II, III and IV only D I,II,III and IV

2 The responding variable of this experiment is A the colour change of the mixture B the interval time taken until all marble chips are dissolved C the change in temperature of the mixture D the rare of the mass of the reaction mixture

3 Which of the following statements correctly describes the hypothesis of this experiment? A The higher the concentration of acid, the smaller the size of marble chips. B The lower the concentration of acid, the greater the volume of gas evolved. C The lower the concentration of acid, the lower the rate of mass loss of the reaction

mixture. D The greater the total mass loss over 3 minutes, the higher the temperature of the

acid.

4 A hypothesis is a statement that shows the relationship between the A fi xed variables and the conclusion B fi xed variable and the inference C fi xed variable and the manipulated variable D manipulated variable and the responding variable

cotton

dilute hydrochloricacid

marble chips

x x x g

conical flask

digital balance

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5 Which of the following is the most suitable form to record quantitative measurement? A Videotaping B Draw diagram C Tabulate the data D Memorising

6 Which of the following is correct about the hypothesis?A A general statement about the relationship between the manipulated variable and the

responding variable B A condition that infl uences the results of the experiment C A smart guess that explains the problem D A series of planned steps done systematically to solve problems

7 Which of the following careers require the knowledge of chemistry? I Doctor II Beautician III Nutritionist IV Accountant A I and III only B II and IV only C I, II and III only D II,III and IV only

Questions 8 – 9 are based on the information below.

8 Problem statement: What is the effect of increasing concentration of sulphuric acid on the rate of its reaction with magnesium ribbon?

Which are the manipulated variable and the fi xed variable for this experiment?

Manipulated variable Fixed variable

A Concentration of sulphuric acid Volume of sulphuric acid B Concentration of sulphuric acid Temperature which reaction occurs C Rate of reaction Concentration of sulphuric acid D Temperature which reaction occurs Concentration of sulphuric acid

9 The rate of reaction between magnesium and dilute sulphuric acid in this experiment is the A manipulated variable B fi xed variable C responding variable D inference

10 Table salt and vinegar are commonly used in our daily life. Which of the following chemicals are contained in table salt and vinegar?

Table salt Vinegar

A Sodium chloride Glucose B Glucose Sodium chloride C Potassium iodide Ethanoic acid D Sodium chloride Ethanoic acid