16 (B410U10-1) Examiner only 13. (a) A compound of carbon, hydrogen and oxygen contains 40.0 % carbon and 6.7 % hydrogen by mass. 1.52 g of the gaseous compound has a volume of 1.76 dm3 at a temperature of 150 °C and a pressure of 1 atm. Use the data to determine the empirical formula and the molecular formula of this compound. You must show clearly how you carried out your calculations. [5] Empirical formula ........................................................ Molecular formula ........................................................ (b) (i) State what is meant by an acid. [1] (ii) Describe how ammonia, NH3, is able to act as a base. [2] (iii) Calculate the pH of 0.43 mol dm–3 hydrochloric acid. [2] pH = ........................................................ © WJEC CBAC Ltd. (B410U10-1) 17 Examiner only (c) In the table below name the type of structure and bonding present in magnesium oxide, MgO, and chlorine dioxide, ClO2. [2] © WJEC CBAC Ltd. Compound Structure Bonding MgO ............................................................. ............................................................. ClO2 ............................................................. ............................................................. 12 Turn over. END OF PAPER 18 (B410U10-1) © WJEC CBAC Ltd. Examiner only For continuation only. (B410U10-1) 19 © WJEC CBAC Ltd. BLANK PAGE