NJC Prelim P1

NATIONAL JUNIOR COLLEGE PRELIMINARY EXAMINATIONS Higher 1 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet 8872/01 22 September 2009 50 minutes READ THE INSTRUCTION FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, Centre number and index number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. This question paper consists of 11 printed pages (including this page).

2 Section A For each qu estion there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1. MnO2 can react with concentrated hydrochloric acid to give chlorine gas as shown by the following equation. MnO2 + 4 HCl  MnCl2 + Cl2 + 2 H2O Given that 1 mole of gas occupies 24 dm 3 at room temperature, calculate the volume of 6 mol dm3 HCl required to generate 500 cm3 of chlorine gas. A 3.50 cm3 C 13.90 cm3 B 8.00 cm3 D 125.00 cm3 2. Which of the following has more protons than electrons and more neutrons than protons? A H 3O+ C Na+ B OH D F 3. The following shows how two ions are deflected in an electric field. Which of the following could be x? A 6Li+ C 27Al3+ B 10B+ D 23Na+ Negative plate  x 16O2 Source Positive plate + [Turn Over

3 4. The number of ions in 10 cm 3 of 0.200 mol dm 3 aqueous calcium chloride is the same as A The number of atoms in 0.426 g of chlorine gas. B The number of protons in 0.041 g of lithium metal. C The number of neutrons in 0.0116 g of aluminium metal. D The number of hydrogen atoms in 0.192 g of methane gas. 5. Ethanamide, CH 3CONH2 was boiled with 100 cm 3 of 1.0 mol dm 3 aqueous NaOH and the NH 3 evolved was passed into 30.00 cm 3 of 1.0 mol dm 3 HCl. The excess acid required 18.25 cm 3 of 0.1 mol dm 3 aqueous NaOH solution for neutralization. Given that ethanamide reacts with NaOH in the following equation. CH3CONH2 + NaOH  CH3COONa + NH3 Calculate the mass of ethanamide used in the reaction. (Mr of CH3CONH2 = 59.0) A 1.66 g C 4.13 g B 3.05 g D 5.90 g 6. Which of the following shows the correct order of the four elements in increasing ionisation energies? A Ga, K, Ca, Ar C K, Ga, Ca, Ar B Ar, K, Ca, Ga D K, Ca, Ga, Ar 7. Which statement about the properties associated with ionic and covalent substances is correct? A Ionic bonds and covalent bonds cannot occur in the same compound. B All covalent compounds are more volatile compared to ionic compounds. C Some ionic and covalent compounds can be electrolytes when dissolved in water. D A covalent compound can form intermolecular hydrogen bonds if it contains hydrogen and either oxygen, nitrogen or fluorine. [Turn Over

4 8. Which of the following molecule is not planar? A H2S C PH3 B BF3 D C2H4 9. X and Y are elements with the following successive ionization energies are plotted on the same axis. 2.5 3 3.5 4 4.5 5 1234567 lg (ionisation energy) X and Y are likely to form a compound of formula: A X3Y2 C XY4 B X2Y3 D X4Y Element X: Element Y: 10. The second ionisation energy of calcium is 1150 kJ mol1. Which of the following correctly represents this statement? A Ca(g) → Ca2+(g) + 2e H = +1150 kJ mol1 B Ca+(g) → Ca2+(g) + e H = +1150 kJ mol1 C Ca+(g) → Ca2+(g) + e H = 1150 kJ mol1 D Ca(s) → Ca2+(g) + 2e H = +1150 kJ mol1 [Turn Over

5 11. Use of the Data Booklet is relevant to this question. Given that the enthalpy of the following reaction is 92 kJ mol 1, calculate the value for the average bond energy of NH bond in ammonia to the nearest whole number. N2 (g) + 3 H2 (g)  2 NH3 (g) A 368 kJ mol1 C 737 kJ mol1 B 399 kJ mol1 D 798 kJ mol1 12. The following equation illustrates the decomposition of H2O2. 2 H2O2 (aq)  O2 (g) + 2 H2O (l) If the rate equation is rate = k [H 2O2] and the rate constant is 0.05 min 1, determine the time taken for the sample of 3.60 mol dm3 H2O2 to decrease to 0.45 mol dm3. A 13.9 min C 41.6 min B 27.7 min D 55.6 min 13. Given the following equilibrium, 2 CrO4 2 (aq) + 2 H+ (aq) Cr2O7 2 (aq) + H2O (l) Yellow Orange Which of the following is true about the above reaction? A CrO 4 2 act as a Bronsted acid. B Chromium in CrO4 2 is oxidised. C The units of the equilibrium constant for the above reaction is mol2 dm6. D When the pH is increased on the equilibrium mixture, the solution turns yellow. 14. A dilute solution of hydrofluoric acid, HF is a weak acid and dissociates as follows: HF (aq) H+ (aq) + F (aq) Given that only 8% of HF is dissociated into ions, calculate the pH of 20 cm 3 of 0.1 mol dm3 HF. A 1.0 C 2.7 B 2.1 D 3.8 [Turn Over

6 15. Given that the energy profile diagra m for a chemical reaction is as follows, Energy/kJ mol1 Reaction progress Which of the following can be deduced from the energy profile diagram? A The reaction involves the formation of two intermediates. B The rate constant of the second step is larger than the first. C When the reaction is carried out, temperature of the surroundings will increase. D The difference between the values of the activation energies of the first and second step is the enthalpy of reaction. 16. Which of the following shows the correct graph for the pH value when the same amount of each oxide is added to 500 cm3 of water? A C B D pH pH 14 7 Na2O MgO Al2O3 SiO2 P4O10 SO 3 Na2O MgO Al2O3 SiO2 P4O10 SO 3 pH pH 14 7 Na2O MgO Al2O3 SiO2 P4O10 SO 3 14 7 14 7 Na2O MgO Al2O3 SiO2 P4O10 SO3 [Turn Over

7 17. Which of th e following is the number of structural isomers for a compound with molecular formula C4H9Cl, excluding cyclic structures? A 3 C 5 B 4 D 6 18. Which of the reactions does the following molecule NOT undergo? C O CH3 A Reduction C Electrophilic addition B Condensation D Electrophilic substitution 19. Which of the following shows a possible synthetic pathway for butanoic acid? A CH 3CH2CH2Cl CH3CH2CH2OH CH3CH2CH2COOH H3CH2CH2COOH D H3CH2CH2Cl CH3CH2CH2CN CH 3CH2CH2COOH B CH 3CH2CH2Cl CH3CH2CH2CN CH3CH2CH2COOH C CH 3CH2CH2CH2Cl CH3CH2CH=CH2 C C KOH (aq), heat MnO4 /H+, heat 2HCN (aq), Cr O /H2 7 + heat KOH, ethanol heat MnO4 /H+, heat KCN, ethanol H+ , (aq) heat heat [Turn Over

8 20. n ester, D with an odour of b