2025 JC2 Prelims H2 Chem Paper 1 Solution_TJC

H2 P1 REVIEW 1 2 3 4 5 6 7 8 9 10 A C B B C B D B B C 11 12 13 14 15 16 17 18 19 20 D A D A B B C C D C 21 22 23 24 25 26 27 28 29 30 A B B C D C D A A B 1 Answer: A Angle of deflection  charge/mass Option A : 2/4 = 0.5 Option B : 1/19 = 0.05 Option C : 1/28 = 0.036 Option D : 2/32 = 0.06 2 Answer: C Cu: 1s2 2s2 2p6 3s2 3p6 3d104s1 Mn: 1s2 2s2 2p6 3s2 3p6 3d5 4s2 Fe: 1s2 2s2 2p6 3s2 3p6 3d6 4s2 Fe2+: 1s2 2s2 2p6 3s2 3p6 3d6 3 Answer: B Option A : [F --- H – F ]–. There is hydrogen bond formed between H in HF and F– as indicated by ---. Option B : Both compounds have hydrogen bonding between molecules. However, volatility depends on the electron cloud size (inferred from Mr) which affects the strength of id-id. Option C : 2-nitrophenol can form intramolecular hydrogen bonding giving rise to less extensive H bonding between molecules and lower melting point. Option D : Ethanoic acid can dimerise in benzene by forming two H bonds between two acid molecules.

4 Answer: B A simple molecular solid should have a low er melting point (due to weak intermolecular forces) and does not conduct electricity (due to lack of mobile charge carriers – ions or free electrons). It may be soluble or insoluble in water depending on the type of intermolecular forces that it can form with water. Since the unknown compound is a solid at room temperature, the answer cannot be A due to the melting point. 5 Answer: C Option 1 has a dative bond from O to C while option 3 has a dative bond from N to O. Option 2 has no dative bond present. 6 Answer: B Vol of original gas mixture = 10 + 50 cm3 Vol of residual gas = ¼ x 60 = 15 cm3 Vol of unreacted O2 = 15 cm3 Vol of reacted O2 = 50 – 15 = 35 cm3 CxHy + (x + y/4)O2 xCO2 + y/2 H2O 10 35 x + y/4 = 35/10 4x + y = 14 x = 2, y = 6 7 Answer: D A: 17 + 4(8) + 1 = 50 e B: 2 + 16 + 4(8) = 50 e C: 16 + 4(8) + 2 = 50 e D: 50 – 2 = 48 e 8 Answer: B During thermal decomposition, heat is absorbed to the reaction, so the reaction is endothermic (option A or B). The activation energy is twice that of the enthalpy change, so option A is incorrect.

9 Answer: B Na(g) → Na+ (g) + e → Na2+(g) + 2e 10 Answer: C Rate = k[L][N] = k[L]2[M] 1: incorrect as Units for k = mol dm–3 s–1 / (mol dm–3)3 = mol–2 dm6 s–1. 2: correct as adding up the 3 elementary steps gives 2L + N → 2P 3: correct. Catalyst is consumed first then regenerated at the end of the reaction while an intermediate is produced and consumed at the end of the reaction. 11 Answer: D Rate = k[W][X]2 Using run 1 data, 0.0064 = k(0.02)(0.015)2, k = 1420 12 Answer: A Using pV = nRT 101000(400x10-6) = n(8.31)(300) n = 0.0162 mol Ar of gas = 40.1 (Ar) 13 Answer: D Option D: By Le Chatelier’s principle, when the experiment is conducted at a lower temperature, the position of equilibrium will shift to the right to release heat as forward react