A student adds green copper(II) carbonate powder to an excess of dilute hydrochloric acid in a beaker. Which observation provides direct evidence that a soluble salt has been formed?
The temperature of the reaction mixture increases.
Effervescence is observed as a gas is released.
The green solid dissolves to form a blue-green solution.
The mixture turns universal indicator red.
276 exam-style questions on Edexcel GCSE Chemistry 4.1 Acids, covering 4.1.1 Acids, alkalis and the pH scale, 4.1.2 Hydrogen ion concentration and pH, 4.1.3 Dilute and concentrated, weak and strong acids, 4.1.4 Bases, alkalis and the reactions of acids, 4.1.5 Chemical tests for hydrogen and carbon dioxide, 4.1.6 Neutralisation as a reaction of acids with bases, 4.1.7 Preparing soluble salts, and 4.1.8 Solubility rules and preparing insoluble salts. Each one has a worked solution and a mark scheme showing where the marks go.