NJC 2019 H1 Promo Paper 1 (QP)

1 NJC Promotional Examination 8873/01/2019 [Turn over NATIONAL JUNIOR COLLEGE SH1 PROMOTIONAL EXAMINATIONS Higher 1 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Optical Answer Sheet Data Booklet 8873/01 Tuesday 1 Oct 2019 40 minutes READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are 20 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. The use of an approved scientific calculator is expected, where appropriate. This document consists of 10 printed pages and 0 blank page.

2 NJC Promotional Examination 8873/01/2019 [Turn over 1 Use of the Data Booklet is relevant to this question. What is the number of atoms in 500 cm3 of oxygen under room conditions? A 1.25 × 1022 B 1.34 × 1022 C 2.50 × 1022 D 2.68 × 1022 2 Gallium nitride, GaN, could revolutionise the design of electric light bulbs because only a small length used as a filament gives excellent light at low cost. GaN is an ionic compound containing the Ga3+ ion. Which statements about GaN are correct? 1 The outer electronic configuration of Ga atom is 4s24p1 since Ga is a Group 13 element. 2 The electron arrangement of the nitrogen ion in GaN is 1s2 2s2 2p3. 3 Ga3+ ion deflects less than Al3+ ion in an electric field. A 1 only B 2 only C 1 and 3 only D 2 and 3 only 3 Oxygen has two isotopes, 16O and 18O. An oxide ion, 𝑂8 𝑥 y–, has the same number of neutrons and electrons. What could be the values of x and y? x y A 16 1 B 16 2 C 18 1 D 18 2 4 Methyl mercaptan, CH3SH, is a substance often used to impart a smell to natural gas in a pipeline. The chemical equation for the combustion of CH3SH is as shown below. CH3SH + 3O2 → CO2 + SO2 + 2H2O A 10 cm3 sample of CH3SH is exploded with 60 cm3 of oxygen and the resultant gas mixture is passed into excess NaOH(aq). What is the percentage of the volume of the resultant gas mixture dissolved in NaOH? [All gas volumes are measured at room temperature and pressure.] A 40.0% B 28.5% C 20.0% D 14.3%

3 NJC Promotional Examination 8873/01/2019 [Turn over 5 Which sketch show the correct trend in the stated property for the elements in Period 3 of the Periodic Table? 1 atomic radius 2 first ionisation energy 3 electrical conductivity A 1 only B 2 only C 1 and 2 only D 2 and 3 only Radius /nm Na Mg Al Si P S Cl First I.E. / kJ mol–1 Na Mg Al Si P S Cl Ar Electrical conductivity Na Mg Al Si P S Cl Ar

4 NJC Promotional Examination 8873/01/2019 [Turn over 6 G is an element in period 4 of the Periodic Table. The first thirteen ionisation energies of G are plotted against the order of the removal of electrons as shown below. What is the formula of the compound formed when G reacts with oxygen? A GO B GO2 C G2O D G2O3 7 In which pair of compounds is the first member less volatile than the second one? A CO2 CS2 B PH3 NH3 C CH3 C C CH3 HH CH3 C C H CH3H D NH3 H2O 8 The shapes of three species P, Q, and R are bent, square planar and trigonal pyrimidal respectively. Which of the following can be P, Q and R? P Q R A CCl2 BrF4− SbF3 B CS2 BH4− ICl3 C F2O ICl4− BCl3 D ICl2− XeF4 SO32− 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Order of electrons removed from X Log (Ionisation Energy) Order of electrons removed from G

5 NJC Promotional Examination 8873/01/2019 [Turn over r q p s C H H C H N H H C O OH I I OHO I I 9 The thyroid gland concentrates iodine and uses it to produce thyroxine, which is a hormone that controls the metabolic rate. Thyroxine What are the values of the bond angles p, q, r and s? p q r s A 180 90 180 90 B 105 90 107 180 C 180 90 120 180 D 105 109.5 107 120 10 Ice is the crystalline form of water. The diagram below shows part of the structure of ice. Which of the following statements is not true about ice? A Ice has a lower density than water at 0 oC due to its open structure. B The bond angle about oxygen in ice is 109.5o. C Ice does not conduct electricity. D The hydrogen bonds are stronger than the O-H covalent bond. Hydrogen bond Covalent bond

6 NJC Promotional Examination 8873/01/2019 [Turn over 11 In which of the following substances, must covalent bonds break on melting? A Phosphorus(V) chloride, PCl5 B Aluminium chloride, Al2Cl6 C Silicon carbide, SiC D Iron(II) hydroxide, Fe(OH)3 12 What is the most likely H value for KOH(aq) + HCl (aq) → KCl(aq) + H2O(l)? Given that NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l) H = −114 kJ mol−1 A −54 kJ mol−1 B −57 kJ mol−1 C −114 kJ mol−1 D −228 kJ mol−1 13 The reaction shown is a first-order reaction. N2O5(g) → 2NO2(g) + ½ O2 (g) Which graph shows how the concentration of N2O5 varies with time? A B C D 0 time [N2O5] 0 time [N2O5] 0 time [N2O5] 0 time [N2O5]

7 NJC Promotional Examination 8873/01/2019 [Turn over 14 The Maxwell–Boltzmann distribution for gas E at a given temperature is shown below. Which statement is correct for the number of molecules with molecular energies A, B and C? A nC decreases when more gas E is added at the same temperature. B nA decreases when temperature is lowered. C nA and nB increases when temperature is increased. D Addition of catalyst at the same temperature has no effect on nA, nB and nC. 15 A chemical plant illegally dumped two radioactive isotopes P and Q in a landfill. The amount of P is 4 times the amount of Q. The radioactive decay of isotopes follows first-order kinetics. The half-life of P is 2 days whereas that of Q is 8 days. By the time the authorities found out about this illegal dumping and analysed a sample of the waste, the ratio of P to Q was found to be 1:2. How long was the waste in the landfill before the authorities arrived? A 8 days B 16 days C 32 days D 64 days A B C nA nC nB n = number of molecules with a given energy molecular energy 0

8 NJC Promotional Examination 8873/01/2019 [Turn over 16 A catalytic converter is part of the exhaust system of many modern cars. Which reactions occur in a catalytic converter? 1 2CO + 2NO → 2CO2 + N2 2 CO2 + NO → CO + NO2 3 2SO2 + 2NO → 2SO3 + N2 A 1 only B 1 and 2 only C 1 and 3 D 1, 2 and 3 17 Which statement is incorrect for the compound shown below? C C C C C N N H H A There are 6 π bonds. B There are 8 σ bonds. C There are two different bond angles. D There are three sp2 hybridised carbons. 18 A halogenoalkane has the formula of C3H5Cl3. Which of the isomers have the correct IUPAC name? 1 1,1,1-trichloropropane 2 1,2,2-trichloropropane 3 2,2,3-trichloropropane A 1 only B 1 and 2 C 2 and 3 D 1, 2 and 3

9 NJC Promotional Examination 8873/01/2019