DHS_H1_CHEM_P1 ANS

Section A For each question, there ar e four possible answers A, B, C, and D. Choos e the one you consider to be correct. 1 When 10.0 cm3 of a 0.10 mol dm–3 solution of alkali metal salt MXO3 was reduced with an excess of acidifi ed potassium iodide solution, the resulting iodine required 60.0 cm 3 of 0.10 mol dm –3 sodium thiosulfate solution for its reduction. The anion could be reduced to A XO2 B XO2– C XO– D X– 2 The use of Data Booklet is relevant to this question. The successive ionization energies, in kJ mol –1, of an element X are given below. 870 1800 3000 3600 5800 7000 13200 What is X? A 33As B 53I C 8O D 52Te 3 Which of the following is a redox reaction? A AlH3 (g) + H– (g)  AlH4 – B Al3+ (aq) + 3OH– (aq)  Al(OH)3 (s) C 2 Al (s) + 3Cl2 (g)  2AlCl3 (s) D AlO2 – (aq) + H+ (aq) + H2O (l)  Al(OH)3 (s) [Turn Over 2

4 10 cm3 of a hydrocarbon was mixed with 100 cm 3 of oxygen gas which is in excess. The mixture was exploded and after it was cooled to room temperature, the residual gases occupied a volume of 80 cm 3. Upon passing the gases through potassium hy droxide, this volume decreased to 50 cm3. What is the formula of the unknown hydrocarbon? A C3H6 B C3H8 C C4H8 D C4H10 5 A sample of 0.025 mol of the chlori de of an element Z was dissolved in distilled water and the solution made up to 500cm 3. 12.5 cm 3 of this solution reacted with 25 cm 3 of 0.1 mol dm –3 silver nitrate solution. What is the most likely formula of the chloride? A Z2Cl B ZCl C ZCl2 D ZCl4 6 Consider the following four compounds: (I) (CH 3)3CH (II) CH3CH2CH2OH (III) CH3CH2CH2SH (IV) CH3CH2CH2CH3 What is the order of the increasing boiling point of the compounds? A I, IV, III, II B II, III, IV, I C III, II, IV, I D IV, I, II, III [Turn Over 3

7 AlCl3 reacts with LiAl H4 and (CH 3)3N to give (CH 3)3NAlH3. Which one of the following will be true of (CH3)3NAlH3? A The Al atom is tetrahedrally coordinated. B The Al atom is electron deficient. C It contains hydrogen bonding. D It is dimeric. 8 When 13.08g of zinc dust was added to 250 cm 3 of 1.0 mol dm –3 aqueous copper (II) sulfate, the temperature of the solution rose by 15C. The specific heat capacity of the final solution is 4.20 J g–1 K–1. Cu2+(aq) + Zn(s)  Zn2+(aq) + Cu(s) What is the enthalpy change for the above reaction? A -82.9 KJ mol–1 B -78.8 KJ mol–1 C -66.3 KJ mol–1 D -4.12 KJ mol–1 [Turn Over 4