2022 YIJC H2 CHEM PRELIM P1 MS

©YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME TEACHER’S COPY CG INDEX NO CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 14 September 2022 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. Write your name and class 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. The use of an approved scientific calculator is expected, where appropriate. This document consists of 16 printed pages.

©YIJC [Turn over 2 1 Use of the Data Booklet is relevant to this question. The table shows the fifth, sixth, seventh, eighth and ninth ionisation energies of an element in the third period. 5th 6th 7th 8th 9th ionisation energy / kJ mol−1 6270 21270 25430 29870 35920 Which element has these ionisation energy values? A P B S C Cl D Ar Answer: A The element is P as there is a large jump between the 5th and 6th ionisation energies as seen in this table. The 6th electron for P is removed from an inner principal quantum shell. 2 Two elements X and Y have the following properties: • X and Y form ionic compounds Na2X and Na2Y respectively. • Element Y forms YF6 molecule whereas X is not able to do so. Which pair of electronic configurations for X and Y is correct? X Y A [He] 2s2 2p4 [He] 2s2 2p2 B [He] 2s2 2p2 [He] 2s2 2p6 3s2 3p3 C [He] 2s2 2p2 [He] 2s2 2p6 3s2 3p2 D [He] 2s2 2p4 [He] 2s2 2p6 3s2 3p4 Answer: D Compounds Na2X and Na2Y show that X and Y forms anions of −2 charge so it means that they have 6 electrons in their valence shell. Y must be a period three element in order for YF6 to exist as it has an expanded octet structure.

©YIJC [Turn over 3 3 Use of the Data Booklet is relevant to this question. An element G forms an ionic nitrate with formula G(NO3)2. In a sample of this compound, the ion G contains 80 electrons and 126 neutrons. Which row describes: • the Group where G is found, • the nucleon number of G in this sample? Group nucleon number A 2 204 B 2 208 C 14 204 D 14 208 Answer: D The formula G(NO3)2 shows that element G can form a +2 cation. G atom has 82 electrons, 82 protons and 126 neutrons, so the nucleon number is 82 + 126 = 208. Hence, G is Pb which is a Group 14 element with a mass number of 207.2 and a nucleon number of 208. 4 The table identifies the shape and polarity of four molecules. Which rows are correct? molecule molecular shape polarity 1 beryllium chloride bent non-polar 2 nitrogen dioxide bent polar 3 sulfur trioxide trigonal planar non-polar 4 chlorine trifluoride trigonal planar polar A 1, 3 and 4 B 2 and 3 C 2, 3 and 4 D 3 and 4

©YIJC [Turn over 4 Answer: B Option 1 is incorrect as BeCl2 is linear, not bent Option 2 is correct as NO2 is bent shaped and is polar Option 3 is correct as SO3 is trigonal planar and non-polar Option 4 is incorrect as ClF3 is T-shaped. 5 Hydrazine, N2H4, and hydrogen peroxide, H2O2, are both used as rocket propellants because they can produce large volumes of hot gases from a small volume of liquid. Which statements about these two compounds are correct? 1 The bond angle in N2H4 is larger than that in H2O2. 2 The N-H bond is shorter than the O-H bond. 3 N2H4 forms stronger intermolecular hydrogen bonds than H2O2. 4 There are  bonds formed by sp3–s orbital overlap in both molecules. A 1 and 4 B 2 and 3 C 1, 2 and 4 D 1, 3 and 4 Answer: A 1 Correct. The bond angle in N2H4 is 107⁰ (3 bp, 1 lp) and the bond angle in H2O2 is 105⁰ (2 bp, 2 lp). 2 Incorrect. The atomic radius of O is smaller than N so the effectiveness of the orbitals overlap is higher and the O-H bond is shorter. 3 Incorrect. The dipole moment of the O -H bond is bigger, hence the hydrogen bonds between the H2O2 molecules are stronger 4 Correct. The electron pairs around N and O are in a tetrahedral arrangement and hence the N and O atoms are sp 3 hybridised and the H atoms consists of s orbitals. The N -H and O-H bonds are formed by sp3 – s orbital overlaps

©YIJC [Turn over 5 6 In an experiment, 0.100 g of a volatile liquid Q formed 0.0250 dm 3 of vapour at 100 ⁰C at 1 bar. What is the relative molecular mass of Q? A 0.100 × 373 0.0250 × 22.7 B 0.0250 × 273 × 22.7 0.100 × 373 C 0.100 × 273 × 22.7 0.0250 × 373 D 0.100 × 373 × 22.7 0.0250 × 273 Answer: D Using pV=nRT (100000)(0.0250 × 10−3) = 0.100 Mr (R)(373) Mr = 0.100 × 373 × R 100000 ×(0.0250 x 10-3) 1 mol of any gas occupies 22.7 dm3 at standard temperature and pressure (100000)(22.7 × 10-3) = R (273) R = 100000 × 22.7 × 10−3 273 Mr = 0.100 × 373 × R 100000 × (0.0250 × 10−3) = 0.100 × 373 × 100000 × 22.7 × 10−3 100000 × (0.0250 × 10−3) × 273 = 0.100 × 373 × 22.7 0.0250 × 273 7 For the elements in Group 17, which trends down the Group are correct? volatility oxidising power A decreases decreases B decreases increases C increases decreases D increases increases

©YIJC [Turn over 6 Answer: A Down Group 17, • size of electron cloud of the halogens increases and more easily polarised • stronger instantaneous dipole induced dipole interactions between molecules exists • more energy needed to overcome the stronger intermolecular forces • boiling point increases • (Since boiling point is inversely proportional to volatility ,) volatility of elements decreases down the group. F2 + 2e− ⇌ 2F− Eo = +2.87 V Cl2 + 2e− ⇌ 2Cl− Eo = +1.36 V Br2 + 2e− ⇌ 2Br− Eo = +1.07 V I2 + 2e− ⇌ 2I − Eo = +0.54 V Down the group, the reactivity of the halogens as oxidising agents decreases as indicated by the less positive Eo values. The halogens have a lower tendency to be reduced. 8 Which statement about relative molecular mass is correct? A It is the sum of the relative atomic masses of all the atoms within the molecule. B It is the ratio of the average mass of a molecule to the mass of a 12C atom. C It is the ratio of the mass of 1 mol of molecules to the mass of 1 mol of 1H atoms D It is the average mass of all the atoms within the molecule. Answer: A A Correct. B Incorrect. Relative molecular mass is the ratio of the average mass of one molecule to one twelfth of the mass of an atom of carbon-12. C Incorrect. Relative molecular mass is the ratio of the average mass of one molecule to one twelfth of the mass of an atom of carbon-12. D Incorrect. Relative molecular mass is not the average mass alone.

©YIJC [Turn over 7 9 The enthalpy change of reaction 1 is –114 kJ mol−1. 2NaOH(aq) + H2SO4(aq) → Na2SO4(aq) + 2H2O(l) reaction 1 By using this information, what is the most likely value for the enthalpy change of reaction 2? NaOH(aq) + CH3COOH(aq) → CH3COONa(aq) + H2O(l) reaction 2 A −50 kJ mol−1 B −57 kJ mol−1 C −114 kJ mol−1 D −228 kJ mol−1 Answer: A In reaction 1, when 2 mol of water is produced heat given out is = 114 kJ In reaction 2, the neutralisatio