CBSE Class 7 Science Exploring Substances: Acidic Basic and Neutral (Class 7 NCERT New) Quiz 1

1. What color does red litmus paper turn when dipped in a basic solution?

A Red B Blue C Green D Yellow

2. Which of the following is an example of an acid?

A Baking soda B Lime water C Vinegar D Soap solution

3. What is the pH value of a neutral substance?

A 0 B 7 C 14 D 10

4. Which of the following substances is a base?

A Lemon juice B Hydrochloric acid C Baking soda D Orange juice

5. What does litmus paper do when it comes in contact with an acidic solution?

A Blue litmus turns red B Red litmus turns blue C Blue litmus turns green D Red litmus turns yellow

6. A student has a solution with a pH of 3. Which of the following best describes this solution?

A Strongly basic B Neutral C Strongly acidic D Weakly basic

7. When an acid and a base are mixed together, which products are formed during neutralization?

A Only water B Only salt C Salt and water D Acid and oxygen

8. A solution has a pH of 11. How would litmus paper react when placed in this solution?

A Red litmus turns blue, indicating a base B Blue litmus turns red, indicating an acid C No change in litmus color D Red litmus turns green, indicating a neutral solution

9. A farmer notices that his crops are not growing well because the soil is too acidic. Which of the following actions should he take to neutralize the soil, and why?

A Add more acid to the soil to balance the pH B Add lime (a base) to the soil to raise the pH and neutralize the acidity C Add vinegar to the soil to lower the pH further D Leave the soil as it is since pH does not affect plant growth

10. A student tests four unknown solutions using litmus paper and records the following results: Solution A turns blue litmus red, Solution B shows no change in either litmus, Solution C turns red litmus blue, and Solution D turns blue litmus red. Which conclusion is most accurate?

A Solutions A and D are bases, Solution B is neutral, and Solution C is an acid B Solutions A and D are acids, Solution B is neutral, and Solution C is a base C All four solutions are acids D Solutions A and C are neutral, while B and D are acids