ACJC 2022 Prelim P1 Answers

© ACJC2022 9729/01/Prelim/2022 ACJC solutions for H2 Chemistry Prelim Paper 1 2022 1 A 11 A 21 C 2 C 12 C 22 A 3 D 13 D 23 A 4 A 14 C 24 C 5 D 15 B 25 B 6 D 16 D 26 C 7 C 17 B 27 B 8 B 18 B 28 A 9 C 19 D 29 C 10 A 20 B 30 B 1 Which species deflects the most in an electric field? A 7Li+ B 24Mg2+ C 32S2− D 27Al3+ Answer: A 7Li+ 24Mg2+ 32S2− 27Al3+ charge mass 1 7 1 12 1 16 1 9 Angle of deflection ∝ charge mass 2 The shape of each p-orbital is represented as two lobes. How many 3d orbitals have four lobes? A 2 B 3 C 4 D 5 Answer: C

© ACJC2022 9729/01/Prelim/2022 3 Which species has the greatest number of unpaired electrons in its ground state? A Cu+ B CH3− C Mg D F Answer: D Cu+: 1s2 2s2 2p6 3s2 3p6 3d10 (no unpaired electrons) CH3−: no unpaired electrons Mg: 1s2 2s2 2p6 3s2 (no unpaired electrons) F: 1s2 2s2 2p5 (1 unpaired electron) 4 Which species contains a dative bond? 1 CO 2 NO3− 3 O3 A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 only Answer: A C O O O O O N O O −

© ACJC2022 9729/01/Prelim/2022 5 Which option correctly describes the shape and polarity of the species? species shape polarity A AlCl3 trigonal planar polar B SiF4 square planar non-polar C BrF3 trigonal pyramidal polar D BeCl2 linear non-polar Answer: D species shape polarity A AlCl3 trigonal planar (3 b.p.) non-polar B SiF4 tetrahedral (4 b.p.) non-polar C BrF3 T shaped (3 b.p. + 2 l.p.) polar D BeCl2 Linear (2 b.p.) non-polar 6 Which graph shows the behaviour of a fixed mass of an ideal gas at a constant temperature? [p = pressure, V = volume, Mr = molar mass, ρ = density] A B C D p ρ pV p pMr V p

© ACJC2022 9729/01/Prelim/2022 Answer: D A pV = nRT pV = r m M RT pMr = k m V B pV = nRT = k C pV = nRT p = 1nRT V   p = k 1 V   D pV = r m M RT p = m V   r RT M    = ρk 7 Which statements explain the difference in ionic radius between Na+ and F−? 1 Outermost electrons of F− experience weaker nuclear charge than those of Na+. 2 Outermost electrons of Na+ experience greater shielding effect than those of F−. 3 Outermost electrons of Na+ are nearer to the nucleus than those of F−. A 3 only B 1 and 2 only C 1 and 3 only D 1, 2 and 3 Answer: C Statement 1: Correct. F− contains fewer protons compared to Na+. Statement 2: Incorrect. Valence electrons of Na+ experience the same shielding effect as those of F− as both species contain the same number of inner shell electrons. pMr V pV p p

© ACJC2022 9729/01/Prelim/2022 Statement 3: Correct. Valence electrons of Na+ are nearer the nucleus than