Important Questions Chapter 2 Class 7 Science Curiosity NCERT

Important Questions For All Chapters – Science Class 7

Exploring Substances: Acidic, Basic, and Neutral

Short Questions

1. What is an acid?

Answer: An acid is a substance that turns blue litmus paper red.

2.What is a base?

Answer: A base is a substance that turns red litmus paper blue.

3.What is a neutral substance?

Answer: A neutral substance does not change the color of litmus paper.

4.What is litmus paper used for?

Answer: Litmus paper is used to test if a substance is acidic or basic.

5.What color does red rose extract turn in an acidic solution?

Answer: It turns red.

6.What happens to turmeric paper in a basic solution?

Answer: It turns red.

7.What is a neutralization reaction?

Answer: It is when an acid and a base mix to form salt and water.

8.Name one natural indicator.

Answer: Red rose extract.

9.What acid is found in lemon juice?

Answer: Citric acid.

10.Why do ant bites sting?

Answer: They inject formic acid into the skin.

Long Questions

1. How can you test if a substance is acidic, basic, or neutral using litmus paper?

Answer: Put a drop of the substance on blue and red litmus paper. If blue turns red, it’s acidic; if red turns blue, it’s basic; if no change, it’s neutral.

2.What happens when you mix an acid with a base?

Answer: They neutralize each other, forming salt and water. Heat is also released in the process.

3.How can red rose extract be used as an indicator?

Answer: Add red rose extract to a substance; it turns red in acidic solutions and green in basic solutions. This shows the nature of the substance.

4.Why is turmeric paper useful for testing basic substances?

Answer: Turmeric paper turns red when a basic substance is applied. It does not change color for acidic or neutral substances.

5. How can neutralization help in daily life, like treating an ant bite?

Answer: An ant bite injects acid, causing pain. Applying a base like baking soda neutralizes the acid and relieves the pain.