2023 NJC H2 Chem Prelim P1 (QP)

1 NJC SH2 Preliminary Examination 9729/01/23 [Turn over NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Optical Answer Sheet Data Booklet 9729/01 14 September 2023 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, 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 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. A Data Booklet is provided. Instructions on how to fill in the Optical Mark Sheet Shade the index number in a 5 digit format on the optical mark sheet: 2nd digit and the last 4 digits of the Registration Number. Example: Student Examples of Registration No. Shade: 2205648 25648 This document consists of 8 printed pages.

2 NJC SH2 Preliminary Examination 9729/01/23 1 Use of the Data Booklet is relevant to this question. Which particle has more protons than electrons and more protons than neutrons? (D = H1 2 ) A D3O+ B H3O+ C NH2− D OD− 2 Cl2 reacts with hot dilute NaOH to give Cl− and ClOx− in a 5:1 ratio. What is the value of x in ClOx−? A 1 B 2 C 3 D 5 3 The boiling point of water (100 C) is greater than that of HF (20 C). Which statement is a correct explanation of this? A Each hydrogen bond formed between water molecules is stronger than that formed between HF molecules. B There are more atoms in a water molecule than there are in an HF molecule, resulting in stronger intermolecular forces in water. C There are on average, more hydrogen bonds between water molecules than there are between HF molecules. D The water molecule has stronger permanent dipole-permanent dipole interactions than the HF molecule. 4 When the carbon-oxygen bonds in methanol, CH3OH, methanal, HCHO, and methanoate, HCO2– are arranged in order of increasing length, what is the correct order? A CH3OH, HCO2–, HCHO B HCO2–,CH3OH, HCHO C HCHO, HCO2–,CH3OH D HCO2–, HCHO, CH3OH

3 NJC SH2 Preliminary Examination 9729/01/23 [Turn over 5 Histamine is produced in the body to help fight infection. Its shape allows it to fit into receptors which expand blood vessels. What are the bond angles x, y and z in histamine, from the smallest to the largest? smallest bond angle largest bond angle A x y z B y x z C y z x D z y x 6 When a sample of a gas is compressed at constant temperature from 1500 kPa to 6000 kPa, its volume changes from 76.0 cm3 to 20.5 cm3. Which statements are possible explanations for this behaviour? 1 The gas behaves non-ideally. 2 The gas partially liquefies. 3 The gas molecules have undergone dimerisation. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only

4 NJC SH2 Preliminary Examination 9729/01/23 7 The table below describes some of the chemistry and thermodynamic properties of the halogens. process name and symbol of quantity 2HX(g) ⎯→ H2(g) + X2(g) H2(g) + X2(g) 2HX(g) X(g) ⎯→ X+(g) + e- enthalpy change of reaction, ∆Hꝋ equilibrium constant, Kp ionisation energy, I.E. Which statements are correct? 1 |∆Hꝋ| for HCl > |∆Hꝋ| for HBr 2 Kp for HBr > Kp for HI 3 I.E. for I > I.E. for Cl A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 8 In a calorimetric experiment 1.60 g of a fuel are burnt. 45.0 % of the energy released is absorbed by 200 g of water. The temperature of the water rises from 18 C to 66 C. What is the total energy released per gram of fuel burnt (to 3 significant figures)? A 25 100 J B 55 700 J C 89 200 J D 373 000 J 9 Consider this gas phase reaction. Cl2(g) + CHCl3 (g) ⎯→ HCl (g) + CCl4 (g) The rate equation for the above reaction is given below. rate = k [CHCl3] [Cl2]1/2 Based on this information, what conclusions can be drawn about this proposed mechanism? Step 1 Cl2 (g) 2Cl (g) Step 2 Cl (g) + CHCl3 (g) ⎯→ HCl (g) + CCl3 (g) Step 3 Cl (g) + CCl3 (g) ⎯→ CCl4 (g) A Step 1 is the rate-determining step. B Step 2 is the rate-determining step. C Step 3 is the rate-determining step. D The rate-determining step cannot be identified.

5 NJC SH2 Preliminary Examination 9729/01/23 [Turn over 10 Ethyl ethanoate undergoes acid-catalysed hydrolysis in water where the concentration of acid in the solution remains constant. CH3CO2CH2CH3 + H2O ⎯→ CH3CO2H + CH3CH2OH The rate equation is found to be rate = k[CH3CO2CH2CH3][H+] In an experiment, when 1.0 mol dm-3 HCl was reacted with 0.20 mol dm-3 ethyl ethanoate, the half-life was found to be 42 min. In a second experiment, 1.0 mol dm-3 HCl was reacted with 0.10 mol dm-3 ethyl ethanoate. What is the half-life of the second experiment? A 10.5 min B 21 min C 42 min D 84 min 11 The equation below shows the reaction of ethanoic acid with ethanol. CH3CO2H(l) + CH3CH2OH(l) CH3CO2CH2CH3 (l) + H2O(l) ethyl ethanoate Which statement is true when the above reaction has attained equilibrium? A The equilibrium constant, K, is equal to 1. B The reaction between the acid and the alcohol has stopped. C The concentrations of the products and reactants are the same. D The rate of formation and the rate of hydrolysis of ethyl ethanoate are the same. 12 Which statements regarding acids and bases are correct? 1 Water can act as either an acid or a base. 2 When AlCl3 reacts with Cl2, the AlCl3 acts as a Lewis acid. 3 The ammonium ion acts as a base when reacted with hydroxide ions. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 13 A 1 dm 3 solution was made by mixing 4.0  10−8 mol of HCl(aq) and 2.5  10−8 mol of NaOH(aq). What is the pH of the resulting solution? A 0.18 B 6.94 C 7.00 D 7.82 H+

6 NJC SH2 Preliminary Examination 9729/01/23 14 A mixture consists of 0.10 mol dm−3 MgSO4 and 0.10 mol dm−3 FeSO4. It is suggested that the metal ions can be separated as their hydroxides by adding solid NaOH to the mixture. At 298 K, the solubility product of Mg(OH)2 is 7.1  10−12 mol3 dm−9 and that of Fe(OH)2 is 4.1  10−15 mol3 dm−9. What would be the pH of the resultant solution when maximum separation has occurred? A 5.07 B 7.30 C 8.93 D 10.10 15 W, X and Y are elements in Period 3 of the Periodic Table. A mixture containing the oxides of W, X and Y was dissolved in excess dilute sulfuric acid and filtered. The oxide of Y was collected as a residue. When excess dilute sodium hydroxide was added to the filtrate, only a white precipitate of the hydroxide of X was formed. What are the possible identities of W, X and Y? W X Y A Mg Al P B Al Mg P C Mg Al Si D Al Mg Si

7 NJC SH2 Preliminary Examination 9729/01/23 [Turn over 16 The graph below shows the trend for a property of X, Y and Z. property ZX Y Which property about X, Y and Z will give the trend shown above? Property X Y Z A pH of the resultant