The document contains questions from a chemistry exam covering topics like rates of reaction, empirical formulas, and chemical equations. Question 1 asks students to identify variables in an experiment investigating the effect of temperature on the rate of reaction between sulfuric acid and magnesium. Question 2 involves drawing a graph of temperature over time and determining the melting point of a substance from the graph. Question 3 covers concepts like nucleon number, electron configuration, and isotopes. Question 4 asks students to determine the empirical formula of magnesium oxide from experimental data.

2. CHEMISTRY FORM 4 PREPARATION FOR STANDARDIZED TEST

3. QUESTION 1: An experiment is conducted to investigate the effect of temperature on the rate of reaction. 5 set of 50cm 3 of 1.0 mol dm -3 sulphuric acid is reacted with 5g of magnesium ribbon at a different temperature.

7. QUESTION 2: A group of students has carried out an experiment to determine the melting point of substance Y. A boiling tube contained substance Y solid is heated in a water bath. The temperature of substance Y is recorded every 30 seconds. The result is as shown in table 2 below.

8. Time (min) 0 ½ 1 1½ 2 2½ 3 3½ Temp. ( o C) 60.0 64.0 68.0 72.0 76.0 80.0 80.0 80.0 Time (min) 4 4 ½ 5 5½ 6 6½ 7 7½ Temp. ( o C) 80.0 80.0 80.0 80.0 80.0 83.0 86.0 89.0

9. a) Draw a graph of the temperature against time for the experiment and locate the melting point for substance Y [4 m]

11. b) Explain why there is no change in temperature from min 2½ to 6 min HEAT ABSORB BY THE PARTICLES IS USE TO OVERCOME THE ATTRACTIVE FORCES BETWEEN THE PARTICLES

12. c) Draw the arrangement of particles at 2 minutes of heating. [1m]

13. QUESTION 3 Table 3 shows the proton number and nucleon number for atom V, W, X, Y and Z Atom Proton number Nucleon number V 1 1 W 1 2 X 3 7 Y 6 12 Z 20 40

17. e) Which of the above atoms are isotopes? Explain your answer. [2 m] V AND W. BOTH ATOMS HAVE SAME PROTON NUMBER BUT DIFFERENT NUCLEON NUMBER OR V AND W. BOTH ATOMS HAVE SAME NUMBER OF PROTON BUT DIFFERENT NUMBER OF NEUTRON

19. Seminar form four= revision for selaras 1- april 2011

27. Rewrite the equation above as chemical equation. [2 m] hydrochloric acid + zinc carbonate  zinc chloride + carbon dioxide + water HCl + 2 ZnCO 3  ZnCl 2 + CO 2 + H 2 O

28. If 12.5 g of zinc carbonate react completely in the reaction above calculate, i) the number of mole of hydrochloric acid being used? [3m]

29. 2HCl + ZnCO 3  ZnCl 2 + CO 2 + H 2 O

30. ii) the mass of zinc chloride obtained. 2HCl + ZnCO 3  ZnCl 2 + CO 2 + H 2 O

31. iii) the vol of gas collected at room temp 2HCl + ZnCO 3  ZnCl 2 + CO 2 + H 2 O