June_2017_QP Paper_1_OCR A Chemistry_AS_Level

1 Which ion has a different number of electrons from the other three ions? A Ga3+ B Cl − C S2− D Ca2+ Your answer [1] 2 An organic compound has the composition by mass: C, 53.33 %; H, 11.11%; O, 35.56%. What is the empirical formula of the organic compound? A C4H8O2 B C4H10O2 C C2H4O D C2H5O Your answer [1] 3 Samples of four hydrocarbons are completely burnt under the same conditions of temperature and pressure. Which sample produces the greatest volume of CO2? A 0.4 mol C2H6 B 0.3 mol C3H8 C 0.2 mol C4H10 D 0.1 mol C5H12 Your answer [1] PMT 3 © OCR 2017 Turn over 4 Which reaction produces the smallest atom economy of BaCl 2? A BaCl 2•2H2O → BaCl 2 + 2H2O B BaO + 2HCl → BaCl 2 + H2O C BaCO3 + 2HCl → BaCl 2 + CO2 + H2O D Ba + 2HCl → BaCl 2 + H2 Your answer [1] 5 The burette readings from a titration are shown below. Final reading / cm3 24.95 Initial reading / cm3 5.00 The burette used has an uncertainty of ±0.05 cm3 in each reading. What is the percentage uncertainty of the resulting titre? A 0.20% B 0.25% C 0.45% D 0.50% Your answer [1] 6 Which element has atoms with the greatest number of singly occupied orbitals? A C B Cl C Ca D Ga Your answer [1] PMT 4 © OCR 2017 7 Which compound has polar molecules? A OCl 2 B BCl 3 C CCl 4 D SCl 6 Your answer [1] 8 Which element has the highest melting point? A silicon B phosphorus C sulfur D chlorine Your answer [1] 9 What is the best explanation for the trend in boiling points down the halogens group? A The covalent bonds become stronger. B The hydrogen bonds become stronger. C The permanent dipole–dipole interactions become stronger. D The induced dipole–dipole interactions (London forces) increase. Your answer [1] PMT 5 © OCR 2017 Turn over 10 Which silver compound is insoluble in concentrated NH3(aq)? A AgNO3 B AgCl C AgBr D AgI Your answer