2020 TJC Qn paper Promo

2 9729 / TJC Promo/ 2020 [Turn over Section A 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 (OMS). 1 The following shows the deflection of two ions in an electric field. Which of the following could be J? A B+11 B Li+7 C Al3+27 D Mg2+24 2 Use of the Data Booklet is relevant to this question. Which of the following species do not have the same number of unpaired electrons as the others? A P+ B Cu3+ C Ca D S Source J x y x > y 16O2– 2020 TJC H2 PROMO MCQ

3 9729 / TJC Promo / 2020 [Turn over 3 Use of the Data Booklet is relevant to this question. Which of the following have the same number of particles as 23.0 g of ethanol, CH3CH2OH, molecules? 1 the number of atoms in 2.125 g of ammonia 2 the number of molecules in 11.35 dm3 of sulfur dioxide at standard temperature and pressure 3 the number of sodium ions in 250 cm3 of 2.0 mol dm-3 sodium carbonate A 1 and 2 B 2 and 3 C 1, 2 and 3 D 2 only 4 Use of the Data Booklet is relevant to this question. A vanadium complex has the formula VO(CxHyOz)2. The percentage composition by mass of the complex is: C, 45.30%; H, 5.29%; O, 30.20%. What is the value of z? A 1 B 2 C 4 D 5 5 The redox reaction between hydrogen sulfide, H 2S, and sulfur dioxide, SO 2, gives elemental sulfur as the only sulfur-containing product. How many moles of sulfur dioxide react with one mole of hydrogen sulfide? A 1 2 B 1 3 C 1 D 2

4 9729 / TJC Promo / 2020 [Turn over 6 Tryptophan is an essential amino acid. Tryptophan What are the approximate bond angles 1, 2 and 3? 1 2 3 A 109.5 90 120 B 120 109.5 120 C 109.5 90 107 D 120 109.5 107 7 The boiling points of ethane and methanal, are as follows: Compound Boiling point /C CH3CH3 Ethane -88.6°C Methanal -19 °C Which of the following statements best explains this difference in boiling points? A Methanal has a larger electron cloud than ethane. B Methanal has a strong C=O bond but not ethane. C Methanal has a permanent dipole but not ethane. D Methanal exhibits intermolecular hydrogen bonding but not ethane. 1 2 3

5 9729 / TJC Promo / 2020 [Turn over 8 Hydrazine, N2H4(l), reacts with dinitrogen tetraoxide, N 2O4(g), to form nitrogen gas and water vapour. 2N2H4(l) + N2O4(g) → 3N2(g) + 4H2O(g) The following data are given. Substance Hfo / kJ mol1 N2H4(l) +50.6 N2O4(g) +9.2 H2O(g) –241.8 What is the enthalpy change for this reaction? A –1077.6 kJ mol–1 B –856.8 kJ mol–1 C –301.6 kJ mol–1 D –182.0 kJ mol–1 9 Sodium burns in oxygen to form Na 2O. Heat energy is given out. The equation for this reaction is shown below. 2Na(s) + ½ O2(g) → Na2O(s) Which of the following statements about the reaction are correct? 1 The magnitude of ∆H○ for the reaction is equal to twice the bond energy of the Na–O bond. 2 ∆H○ for the reaction is negative. 3 The equation represents the standard enthalpy change of combustion of sodium. 4 The equation represents the standard enthalpy change of formation of sodium oxide. A 1, 2, 3 and 4 B 2, 3 and 4 C 3 and 4 D 2 and 4

6 9729 / TJC Promo / 2020 [Turn over 10 When 0.04 mol of propan -2-ol, C3H8O, was burned under a container of water , only 80% of the heat from the combustion of propan-2-ol was absorbed by the water. It was found that the water was heated from 25C to 80C. Given that the standard enthalpy change of combustion of propan -2-ol is –2005 kJ mol-1, what is the mass of water heated in this reaction? [You may use 4.18 J g-1 K-1 for the specific heat capacity of water.] A 277 g B 279 g C 349 g D 463 g 11 Which of the following statements is correct for a reaction in which the equilibrium constant does not change with temperature? A The rate constants for the forward and reverse reactions do not vary with temperature. B The activation energy of both forward and reverse reactions are zero. C There are equal numbers of moles of reactants and products. D The enthalpy change for the reaction is zero. 12 A sample of (NH4)2SO4(s) was placed in a 1 dm 3 enclosed vessel and allowed to dissociate at 330oC as follows: (NH4)2SO4(s) ⇌ 2NH3(g) + H2SO4(g) The value of Kc is 2.57 x 10-5. What will be the concentration of H2SO4 at equilibrium? A 0.00358 B 0.0186 C 0.0295 D 0.0371

7 9729 / TJC Promo / 2020 [Turn over 13 The decomposition of a sample of hydrogen peroxide in the presence of manganese (IV) oxide is as follows. 2H2O2  2H2O + O2 A study of the rate of this reaction gave the following results. Time after the start of reaction / s Volume of O2 produced / cm3 0.0 0 10.0 27 20.0 50 30.0 68 40.0 75 50.0 100 60.0 100 Which conclusions can be drawn about the kinetics of this reaction? 1 The half-life is 20 s. 2 The reaction is first order with respect to [H2O2]. 3 The overall reaction is second order. A 2 only B 1 and 2 C 1 and 3 D 2 and 3 14 For a reversible reaction, the rate constants for the forward reaction and reverse reactions are kf and kb respectively, while Kc is the equilibrium constant. Which of the following statements is true of the effect of a catalyst on kf, kb and Kc? kf kb Kc A increase decrease no effect B increase decrease increase C increase increase no effect D no effect no effect increase

8 9729 / TJC Promo / 2020 [Turn over 15 When a sample of gas at a constant temperature is compressed, pressure increases from 20 atm to 50 atm and the volume decreases from 96 cm3 to 46 cm3. Which of the following statements best explains this behaviour? A The gas particles have significant volume c ompared to the volume of the container. B There are significant intermolecular forces of attraction between the gas particles. C The collisions between the gas particles are not perfectly elastic. D The gas particles are in a state of continuous random motion. 16 The following diagram shows the contents of three vessels which are joined together by a connecting tube of volume, V dm3 in which air has been removed. After the valves of the vessels were opened, the final pressure at 30oC is measured to be 0.68 atm. The gases do not react with each other. If all the vessels and connecting tube are maintained at 30oC, what is the volume, V, of the connecting tube? A 0.037 dm3 B 0.074 dm3 C 0.392 dm3 D 5.07 dm3 17 Which of the following is always true for an electrophile? 1 It accepts a pair of electrons. 2 It is a cation. 3 It is attracted to electron rich sites. A 3 only B 1 and 2 C 1 and 3 D 2 and 3

9 9729 / TJC Promo / 2020 [Turn over 18 Methane reacts with excess chlorine in the presence of ultraviolet light. Which of the following product will not be formed? A H2 B HCl C CH2Cl2 D CH3CH2Cl 19 A sample of propene was reacted with bromine dissolved in aqueous hydrochloric acid. Which of the following products will not be formed in the reaction? A B C D 20 Prismane is a polycyclic hydrocarbon which is an isomer of benzene. Prismane When prismane undergoes reaction with bromine gas under uv light, it forms a compound C6H4Br2. How many constitutional isomers would this compound have? A 2 B 3 C 5 D 6

10 9729 / TJC Promo / 2020 [Turn over Blank Page

11 9729 / TJC Promo / 2020 [Turn over Blank Page