Grade 9 · CAPS

Grade 9 Acids and Bases

Natural Sciences and Technology practice questions with answers

Grade 9 Acids and Bases is part of the CAPS Natural Sciences and Technology curriculum, covering the pH scale, how indicators are used to identify acids and bases, and the everyday examples of each. Learners practise ordering substances from most to least acidic, defining pH, reading indicator colour changes, and distinguishing acids, alkalis and neutral substances. The practice questions below are drawn from ReClass's own question bank, based on real Grade 9 CAPS assessments, giving learners a chance to work through acids-and-bases questions in the same style they will meet in a test.

Worked example

Sulphur burns in oxygen and the white fumes formed turn moist blue litmus paper red. Is the resulting oxide acidic, basic or neutral?

Answer & explanation

Acidic

You'll also practise

  • 1.6 Which of the following substances is considered acidic on the pH scale?
  • Which combination below is an example of an ACID and a BASE?
  • Arrange the following substances from MOST acidic to LEAST acidic: hydrochloric acid, lemon juice, black coffee, sodium chloride, calcium carbonate, magnesium oxide, bleach.
  • State the relationship between the pH of a substance and its acidity.
  • Black coffee has a pH of about 5. Explain why black coffee would not be a good remedy for heartburn.
  • Give the correct term: a base that is soluble in water.
  • Water has a pH of 7. Give the correct term for this type of substance.
  • Vinegar tastes sour and has a pH value below 7. Give the correct term for this type of substance.
  • Define the term pH.
  • On a pH scale, which substance would be more basic: drain cleaner or soap?
  • On a pH scale, which substance would be more acidic: coffee or lemon?
  • If a solution is acidic, it can be neutralised by adding …
  • Which indicator is green in a neutral solution?

Common mistakes

  • Thinking a higher pH number means a substance is more acidic, when the opposite is true.
  • Confusing an alkali (a soluble base) with a base in general.
  • Misreading an indicator's colour scale when identifying whether a solution is acidic or basic.

Aligned to CAPS Grade 9 Natural Sciences and Technology — Acids and Bases.

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