From Atoms to Materials

Checkpoint 13.4A 1. (a) A is a pure substance made up of two or more elements chemically combined together. (b) A consists of two or more pure substances that are not chemically combined together. 2. Circle T for a true statement and F for a false one. (a) A mixture must be an impure substance. T / F (b) Air is an example of a compound. T / F (c) Some compounds may be broken down into their constituent elements by electricity. T / F (d) The properties of a mixture are different from those of its constituent substances. T / F 3. In a burning candle, three processes are happening, as shown below: (a) Which of these processes is/are physical changes? (b) Which of these processes is/are chemical changes? What new substance(s) is/are formed? A. Solid wax melts to become a liquid. B. Liquid wax is becoming gaseous wax. C. The gas burns. C A B 54 © United Prime Educational Publishing (HK) Limited 2024 All rights reserved; no part of this publication may be reproduced, photocopied, recorded or otherwise, without the prior written permission of the Publisher. Sample