Year 9 Science – Acids and Bases Review

Year 9 Science – Acids and Bases Practice Test Answers

Overview

  • This document contains the answers to a Year 9 science practice test focused on the themes of acids and bases.

  • The total marks for the test are out of 34.

  • The test is structured with multiple-choice questions, examples, and descriptive questions.

Questions 1-6: Multiple Choice

  • Each question is worth one mark.

  1. Acids generally:

    • A. taste bitter

    • B. taste sour

    • C. feel slippery

    • D. are coloured.

  2. Bases:

    • A. unlike dangerous acids, are generally quite safe

    • B. are just a stronger type of acid

    • C. are found in citrus fruits

    • D. are used in many cleaning products.

  3. Adding liquid X to water decreases its pH. This shows that liquid X is:

    • A. an acid

    • B. a base

    • C. neutral.

  4. Antacid tablets contain:

    • A. a special medicinal acid extracted from ants

    • B. alternative acids for dissolving food that are milder than stomach acid

    • C. substances designed to speed up the action of stomach acid on food

    • D. a chemical which dissolves in the stomach to release a base.

  5. Which list shows four substances in order from the strongest acid to the strongest base?

    • A. Vinegar, tomato juice, toothpaste, oven cleaner

    • B. Tomato juice, toothpaste, vinegar, oven cleaner

    • C. Oven cleaner, vinegar, tomato juice, toothpaste

    • D. Toothpaste, tomato juice, oven cleaner, vinegar

  6. The name given to a reaction in which an acid and a base are mixed to produce water and a salt is:

    • A. cancellation

    • B. destruction

    • C. neutralisation

    • D. elimination.

Questions 7-12: Short Answer

  1. When an acid reacts with a metal the products are:

    • A. water and carbon dioxide

    • B. carbon dioxide and a salt

    • C. a salt and hydrogen gas

    • D. hydrogen and oxygen.

  2. Which of the following contribute to acid rain? (There is more than one answer.)

    • A. Oxygen

    • B. Carbon dioxide

    • C. Active volcanoes

    • D. Pollution

    • E. Rock and roll groups

  3. Give two common examples of:
    a) Acids: hydrochloric, sulphuric, phosphoric, carbonic, nitric, and other answers possible
    b) Bases: sodium hydroxide, magnesium oxide, ammonia, and other answers possible.

    • Do not use the examples given in previous questions. [2]

  4. Describe a possible use of:
    a) sulfuric acid: car batteries, production of fertilisers, and other answers possible.
    b) Ammonia solution: oven cleaning, fertiliser, and other answers possible. [2]

  5. What is universal indicator? What has it got to do with pH?

    • It’s a mixture of indicators that changes colour as the pH of a solution changes. It gives an indication of pH. [2]

  6. The pH of water in a swimming pool is 7.9. The ideal pH is 7.6. What should you be adding to the pool water to make the pH lower – water, alkali, or acid?

    • Acid

Questions 13-16: Word Equations and Matching

  1. Complete the following word equations: [6]

    • Hydrochloric acid + Sodium Hydroxide → sodium chloride + water

    • Sulfuric acid + Magnesium → magnesium sulphate + hydrogen

    • Nitric Acid + Potassium carbonate → water + potassium nitrate + carbon dioxide

  2. Match a term in the box with each description: [7]

    • a) Acids turn blue litmus to red.

    • b) Acids react with metals to produce hydrogen gas.

    • c) Acids react with marble chips (calcium carbonate) to produce carbon dioxide gas.

    • d) A base which is water-soluble is called an alkali.

    • e) A basic solution will have a pH that is higher than seven.

    • f) A substance which can tell you if a solution is an acid or base is called an indicator.

    • g) A solution which is not an acid or base is said to be neutral.

  3. Refer to the table below. [3]

    • Classification: Strong acid, Moderate acid, Weak acid, Neutral, Weak base, Moderate base, Strong base.

    • (a) Put the words Neutral, Weak acid, Moderate acid, Strong acid, Weak base, Moderate Base, and Strong Base into the correct boxes above.

    • (b) Explain why this red cabbage indicator is more useful than an indicator such as litmus for determining the acidity or basicity of a solution:

      • It changes to a range of colours depending on the pH so that one can determine the approximate strength of the acid or base, whereas litmus only changes to red for acids and blue for bases and is thus less accurate. [1]

  4. (a) Sherbet contains a mixture of citric acid and baking soda (or “sodium hydrogen carbonate”). Baking soda reacts in the same way that all carbonates do with acid. Name the gas produced:

    • Carbon dioxide. [1]

    • (b) Describe a test for this gas:

      • Either: A burning splint is extinguished.

      • Or: Bubble the gas through limewater. If the limewater changes from colourless to milky/cloudy then the gas present is carbon dioxide. [1]