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ScienceAges 16-18

Acids, bases & the pH scale

Use the 0–14 pH scale, indicators and neutralisation reactions to classify acidic, neutral and alkaline solutions. Review suitability for your learners before teaching.

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Worksheet StudioPractice pack · Ages 16-18

Acids, bases & the pH scale

Take your time. Show your thinking.

  1. 1. What is the chemical test that confirms a gas is carbon dioxide (CO₂): it turns clear limewater cloudy (milky), or it relights a glowing splint?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  2. 2. In an acid–base titration, which piece of graduated glassware with a tap at the bottom is used to measure the exact volume of acid or alkali added: a burette or a beaker?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  3. 3. What colour does red litmus paper turn when dipped into an alkaline solution: blue or yellow?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  4. 4. What weak organic acid gives vinegar its sour taste: ethanoic (acetic) acid or nitric acid?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  5. 5. What colour does blue litmus paper turn when dipped into an acidic solution: red or blue?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  6. 6. Why do indigestion tablets (antacids) contain mild bases such as magnesium hydroxide or calcium carbonate: to neutralise excess stomach acid, or to add more acid?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  7. 7. Why do farmers sometimes spread powdered calcium carbonate (limestone) or calcium oxide on fields: to neutralise overly acidic soil, or to make the soil more acidic?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  8. 8. What weak organic acid is found naturally in lemons, limes and oranges: citric acid or sulfuric acid?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  9. 9. What colour does Universal Indicator turn in a neutral solution of pH 7: green or red?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  10. 10. Which salt is formed when hydrochloric acid (HCl) is neutralised by sodium hydroxide (NaOH): sodium chloride or sodium sulfate?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  11. 11. What is the chemical test that confirms a gas is oxygen (O₂): it relights a glowing wooden splint, or it turns limewater milky?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  12. 12. Does an acidic solution (such as lemon juice or hydrochloric acid) have a pH less than 7 or greater than 7?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution
12 questions · Seed 104730 · Age guidance, not curriculum certification
View the answer key
Worksheet StudioAnswer key · Ages 16-18

Acids, bases & the pH scale

Answers and reasoning. Review before teaching.

  1. 1. What is the chemical test that confirms a gas is carbon dioxide (CO₂): it turns clear limewater cloudy (milky), or it relights a glowing splint?

    It turns clear limewater cloudy (milky)

    CO₂ reacts with calcium hydroxide (limewater) to form an insoluble white precipitate of calcium carbonate.

  2. 2. In an acid–base titration, which piece of graduated glassware with a tap at the bottom is used to measure the exact volume of acid or alkali added: a burette or a beaker?

    Burette

    A burette delivers variable volumes accurately to within 0.05 cm³.

  3. 3. What colour does red litmus paper turn when dipped into an alkaline solution: blue or yellow?

    Blue

    Alkalis turn red litmus paper blue.

  4. 4. What weak organic acid gives vinegar its sour taste: ethanoic (acetic) acid or nitric acid?

    Ethanoic (acetic) acid

    Vinegar is a dilute aqueous solution of ethanoic (acetic) acid.

  5. 5. What colour does blue litmus paper turn when dipped into an acidic solution: red or blue?

    Red

    Acids turn blue litmus paper red.

  6. 6. Why do indigestion tablets (antacids) contain mild bases such as magnesium hydroxide or calcium carbonate: to neutralise excess stomach acid, or to add more acid?

    To neutralise excess stomach acid

    Antacids are weak bases that neutralise excess hydrochloric acid in the stomach.

  7. 7. Why do farmers sometimes spread powdered calcium carbonate (limestone) or calcium oxide on fields: to neutralise overly acidic soil, or to make the soil more acidic?

    To neutralise overly acidic soil

    Basic calcium compounds neutralise excess soil acidity so crops can grow well.

  8. 8. What weak organic acid is found naturally in lemons, limes and oranges: citric acid or sulfuric acid?

    Citric acid

    Citrus fruits contain citric acid.

  9. 9. What colour does Universal Indicator turn in a neutral solution of pH 7: green or red?

    Green

    Universal Indicator is green at neutral pH 7, red in strong acid, and purple in strong alkali.

  10. 10. Which salt is formed when hydrochloric acid (HCl) is neutralised by sodium hydroxide (NaOH): sodium chloride or sodium sulfate?

    Sodium chloride

    HCl + NaOH → NaCl (sodium chloride) + H₂O.

  11. 11. What is the chemical test that confirms a gas is oxygen (O₂): it relights a glowing wooden splint, or it turns limewater milky?

    It relights a glowing wooden splint

    Pure oxygen supports rapid combustion and relights a glowing splint.

  12. 12. Does an acidic solution (such as lemon juice or hydrochloric acid) have a pH less than 7 or greater than 7?

    Less than 7

    Acids have pH values below 7; the lower the pH, the stronger or more concentrated the acid.

12 questions · Seed 104730 · Age guidance, not curriculum certification
Worksheet StudioPractice pack · Ages 16-18

Acids, bases & the pH scale

Take your time. Show your thinking.

  1. 1. What is the chemical test that confirms a gas is carbon dioxide (CO₂): it turns clear limewater cloudy (milky), or it relights a glowing splint?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  2. 2. In an acid–base titration, which piece of graduated glassware with a tap at the bottom is used to measure the exact volume of acid or alkali added: a burette or a beaker?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  3. 3. What colour does red litmus paper turn when dipped into an alkaline solution: blue or yellow?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  4. 4. What weak organic acid gives vinegar its sour taste: ethanoic (acetic) acid or nitric acid?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  5. 5. What colour does blue litmus paper turn when dipped into an acidic solution: red or blue?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  6. 6. Why do indigestion tablets (antacids) contain mild bases such as magnesium hydroxide or calcium carbonate: to neutralise excess stomach acid, or to add more acid?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  7. 7. Why do farmers sometimes spread powdered calcium carbonate (limestone) or calcium oxide on fields: to neutralise overly acidic soil, or to make the soil more acidic?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  8. 8. What weak organic acid is found naturally in lemons, limes and oranges: citric acid or sulfuric acid?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  9. 9. What colour does Universal Indicator turn in a neutral solution of pH 7: green or red?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  10. 10. Which salt is formed when hydrochloric acid (HCl) is neutralised by sodium hydroxide (NaOH): sodium chloride or sodium sulfate?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  11. 11. What is the chemical test that confirms a gas is oxygen (O₂): it relights a glowing wooden splint, or it turns limewater milky?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution

  12. 12. Does an acidic solution (such as lemon juice or hydrochloric acid) have a pH less than 7 or greater than 7?

    pH Scale: 0 (Acid) → 7 → 14 (Alkali) · Indicator Solution
12 questions · Seed 104730 · Age guidance, not curriculum certification
Worksheet StudioAnswer key · Ages 16-18

Acids, bases & the pH scale

Answers and reasoning. Review before teaching.

  1. 1. What is the chemical test that confirms a gas is carbon dioxide (CO₂): it turns clear limewater cloudy (milky), or it relights a glowing splint?

    It turns clear limewater cloudy (milky)

    CO₂ reacts with calcium hydroxide (limewater) to form an insoluble white precipitate of calcium carbonate.

  2. 2. In an acid–base titration, which piece of graduated glassware with a tap at the bottom is used to measure the exact volume of acid or alkali added: a burette or a beaker?

    Burette

    A burette delivers variable volumes accurately to within 0.05 cm³.

  3. 3. What colour does red litmus paper turn when dipped into an alkaline solution: blue or yellow?

    Blue

    Alkalis turn red litmus paper blue.

  4. 4. What weak organic acid gives vinegar its sour taste: ethanoic (acetic) acid or nitric acid?

    Ethanoic (acetic) acid

    Vinegar is a dilute aqueous solution of ethanoic (acetic) acid.

  5. 5. What colour does blue litmus paper turn when dipped into an acidic solution: red or blue?

    Red

    Acids turn blue litmus paper red.

  6. 6. Why do indigestion tablets (antacids) contain mild bases such as magnesium hydroxide or calcium carbonate: to neutralise excess stomach acid, or to add more acid?

    To neutralise excess stomach acid

    Antacids are weak bases that neutralise excess hydrochloric acid in the stomach.

  7. 7. Why do farmers sometimes spread powdered calcium carbonate (limestone) or calcium oxide on fields: to neutralise overly acidic soil, or to make the soil more acidic?

    To neutralise overly acidic soil

    Basic calcium compounds neutralise excess soil acidity so crops can grow well.

  8. 8. What weak organic acid is found naturally in lemons, limes and oranges: citric acid or sulfuric acid?

    Citric acid

    Citrus fruits contain citric acid.

  9. 9. What colour does Universal Indicator turn in a neutral solution of pH 7: green or red?

    Green

    Universal Indicator is green at neutral pH 7, red in strong acid, and purple in strong alkali.

  10. 10. Which salt is formed when hydrochloric acid (HCl) is neutralised by sodium hydroxide (NaOH): sodium chloride or sodium sulfate?

    Sodium chloride

    HCl + NaOH → NaCl (sodium chloride) + H₂O.

  11. 11. What is the chemical test that confirms a gas is oxygen (O₂): it relights a glowing wooden splint, or it turns limewater milky?

    It relights a glowing wooden splint

    Pure oxygen supports rapid combustion and relights a glowing splint.

  12. 12. Does an acidic solution (such as lemon juice or hydrochloric acid) have a pH less than 7 or greater than 7?

    Less than 7

    Acids have pH values below 7; the lower the pH, the stronger or more concentrated the acid.

12 questions · Seed 104730 · Age guidance, not curriculum certification