Worksheets With Solutions: Acids, Bases and Salts Class 7 Worksheet Science Chapter 2

Section A: Multiple Choice Questions

Correct Answer is Option (a)
Lemon juice contains citric acid which makes it acidic in nature.

Q.2. What is the pH value of a neutral substance?
(a) 7
(b) 0
(c) 14
(d) 1

Correct Answer is Option (a)
pH value of 7 is considered neutral as it is neither acidic nor basic.

Q.3. Which indicator is used to test for acidity?
(a) Methyl orange
(b) Phenolphthalein
(c) Litmus paper
(d) None of the above

Correct Answer is Option (c)

Litmus paper turns red in acidic solutions and blue in basic solutions.

Q.4. What is the chemical formula of hydrochloric acid?
(a) HCl
(b) NaOH
(c) CaCO₃
(d) H₂SO₄

Correct Answer is Option (a)
Hydrochloric acid is a strong acid with a pH of 1 and its chemical formula is HCl.

Q.5. Which of the following is a salt?
(a) Vinegar
(b) Sugar
(c) Sodium chloride
(d) Lemon juice

Correct Answer is Option (a)
Sodium chloride is a compound made up of sodium and chlorine and is commonly used as table salt.

Section B: Short Questions

Acids are used in various industries like food, medicine, and chemical manufacturing. For example, hydrochloric acid is used to clean metals, while citric acid is used in food and beverage production.

Q.2. What is a basic substance?

A basic substance is one that has a pH value greater than 7. Examples of basic substances are baking soda and soap.

Q.3. Name two indicators used to test for acidity and basicity.

Methyl orange and phenolphthalein are two indicators used to test for acidity and basicity.

Q.4. What are salts and how are they formed?

Salts are compounds that are formed when an acid reacts with a base. For example, sodium chloride is formed when hydrochloric acid reacts with sodium hydroxide.

Q.5. Give an example of a salt commonly used in cooking.

An example of a salt commonly used in cooking is sodium chloride or table salt.

Section C: Fill in the blanks (5 marks)

Acid is a substance that turns blue litmus red. Litmus paper is used to test whether a substance is acidic or basic. When blue litmus paper is dipped in an acidic solution, it turns red.

Q.2. __________ is a substance that turns red litmus blue.

Base is a substance that turns red litmus blue. When red litmus paper is dipped in a basic solution, it turns blue.

Q.3. __________ is used to make fertilizers and detergents.

Sodium chloride is used to make fertilizers and detergents. It is also commonly known as table salt.

Q.4. __________ is a common acid found in citrus fruits.

Citric acid is a common acid found in citrus fruits such as lemons and oranges.

Q.5. __________ is a compound formed when an acid reacts with a base.

A salt is a compound formed when an acid reacts with a base. For example, when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), sodium chloride (NaCl) is formed.

Section D: Match the column (5 marks)

Section E: True False (5 marks)

True
Acids have a sour taste. For example, lemon juice is sour because it contains citric acid. 

Q.2. Bases have a pH value of less than 7.

False
Bases have a pH value of more than 7, not less than 7. A pH value of 7 is considered neutral.

Q.3. Vinegar is a base.

False
Vinegar is an acid, not a base. It is made of acetic acid.

Q.4. Indicators are used to test for the presence of acids or bases.

True
Indicators are used to test for the presence of acids or bases. When an indicator comes into contact with an acidic solution, it changes color.

Q.5. Common salt is an example of a base.

False
Common salt, or sodium chloride (NaCl), is an example of a neutral substance, not a base.