ACID BASE &SALT

 

Worksheet 1 

Acid, Base, and Salt

Class: 7
Subject: Science

Section A: Fill in the Blanks

  1. Substances that taste sour are called __________.
  2. __________ is a natural indicator that turns red in acidic solutions and green in basic solutions.
  3. Bases are __________ to touch and turn red litmus __________.
  4. The chemical formula of hydrochloric acid is __________.
  5. __________ is a base used to make soaps and detergents.

Section B: True or False

  1. Bases are bitter in taste and turn blue litmus red. (True/False)
  2. Acidic substances are found in lemon and vinegar. (True/False)
  3. Neutral substances do not change the color of any indicator. (True/False)
  4. Ammonium hydroxide is an example of an acid. (True/False)
  5. Salt is formed by the reaction between an acid and a base. (True/False)

Section C: Match the Following

Column AColumn B
1. Acid in tamarinda. Sodium chloride
2. Base in soapb. Citric acid
3. Salt in common usec. Hydrochloric acid
4. Indicator in turmericd. Sodium hydroxide
5. Acid in stomache. Turns red in base

Section D: Short Answer Questions

  1. What are acids and bases? Give two examples of each.
  2. Write the difference between a strong acid and a weak acid.
  3. What is the importance of neutralization in everyday life? Give one example.
  4. Why are indicators used in testing substances? Name two natural indicators.
  5. How is salt formed? Write an example of a chemical reaction.

Section E: Long Answer Questions

  1. Describe the reaction between acids and bases with an example. Explain how salts are formed during the reaction.
  2. Explain the role of indicators in determining whether a substance is acidic, basic, or neutral. Include examples of synthetic and natural indicators.

Section F: Activities

  1. Test at Home: Collect substances like lemon juice, soap water, vinegar, and sugar solution. Use turmeric paper or litmus paper to test their nature (acidic, basic, or neutral). Record your observations.
  2. Neutralization Experiment:
    • Take a small amount of vinegar and add baking soda to it.
    • Observe the reaction. What do you notice? Explain the change in the reaction mixture.

Section G: Diagram-Based Questions

  1. Draw a labeled diagram showing the neutralization reaction in a test tube.
  2. Illustrate and label a litmus test for an acidic, basic, and neutral solution.



Worksheet 2

Acid, Base, and Salt

Class: 7
Subject: Science

Section A: Multiple Choice Questions (MCQs)

  1. Which of the following turns blue litmus red?
    a) Vinegar
    b) Soap water
    c) Baking soda
    d) Sugar solution

  2. A substance that tastes bitter and feels soapy is likely to be:
    a) Acid
    b) Base
    c) Salt
    d) Neutral

  3. What is the pH of a neutral solution?
    a) 1
    b) 7
    c) 10
    d) 14

  4. Which of these is a natural indicator?
    a) Phenolphthalein
    b) Methyl orange
    c) Litmus
    d) Sodium hydroxide

  5. The salt formed by the reaction of hydrochloric acid and sodium hydroxide is:
    a) Potassium chloride
    b) Sodium chloride
    c) Ammonium chloride
    d) Calcium carbonate

Section B: Fill in the Blanks

  1. Acids produce __________ ions when dissolved in water.
  2. Bases react with acids to form __________ and __________.
  3. __________ is a synthetic indicator that turns pink in basic solutions.
  4. The __________ in turmeric changes color in the presence of bases.
  5. Baking soda is a __________, and it is used in cooking to make food soft and fluffy.

Section C: Answer in One Word

  1. Name the acid found in curd.
  2. Which base is used in antacids to relieve stomach acidity?
  3. Write the chemical formula of sodium hydroxide.
  4. What is the taste of bases?
  5. Which acid is found in lemon?

Section D: Short Answer Questions

  1. What is an indicator? Name one natural and one synthetic indicator.
  2. Write the chemical equation for the reaction between hydrochloric acid and sodium hydroxide.
  3. What is neutralization? Provide one example from daily life.
  4. Why is baking soda used in antacids?
  5. Explain why vinegar is used to clean stains caused by lime deposits.

Section E: Match the Following

Column AColumn B
1. Acetic acida. Used in batteries
2. Hydrochloric acidb. Found in vinegar
3. Calcium hydroxidec. Slaked lime
4. Sulfuric acidd. Found in the stomach
5. Sodium chloridee. Common table salt

Section F: True or False

  1. Acids are bitter in taste and turn blue litmus red.
  2. Salts are always neutral in nature.
  3. Bases release hydroxide ions in water.
  4. Turmeric is a synthetic indicator.
  5. Washing soda is a base used in the preparation of glass.

Section G: Diagram-Based Questions

  1. Draw and label a pH scale showing acidic, basic, and neutral solutions.
  2. Illustrate and explain how turmeric can be used as an indicator to test a solution’s nature.

Section H: Activity-Based Learning

  1. Test the Nature of Substances

    • Collect the following items: lemon juice, milk, detergent, and sugar solution.
    • Test each with litmus paper and record the changes in color.

  2. Neutralization Reaction:

    • Mix a small amount of vinegar with baking soda.
    • Write your observations and explain what happens.
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