MEDIUM
7th Kerala Board
IMPORTANT
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Are there other flowers that can be used as indicators like the hibiscus? Examine.

Important Questions on Acids and Alkalis

MEDIUM
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 1>Q 1

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Didn’t you read the diary? How did the red letters appear on the board? Does the magician have any extraordinary power?
MEDIUM
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 2>Q 2
What could be the reason for the appearance of red flowers on the plant?
EASY
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 2>Q 4
Rub a hibiscus flower on a piece of paper. Pour one or two drops of lemon juice on it. The colour change is observed. Which of the substances we commonly use have this property?
MEDIUM
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 2>Q 5
Conduct an experiment with hibiscus paper on buttermilk, water, coconut oil, vinegar, soap solution, sugar solution, salt solution, tamarind water and milk. Which are the liquids that turned the hibiscus paper red?
EASY
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 3>Q 1

Have you noticed the bottle and its stopper, used to store acid in the laboratory? Why are metal stoppers not used?

MEDIUM
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 3>Q 2

The pickles we commonly use are acidic in nature. Are they stored in metal containers?

MEDIUM
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 4>Q 1

You can dip red hibiscus paper and red litmus paper in water, buttermilk, vinegar, soap solution, lime water, salt solution, sugar solution, milk and clear ash suspension, and observe what happens. Which are the liquids in which red hibiscus paper turns blue? Which are the liquids in which red litmus paper turns blue?

MEDIUM
7th Kerala Board
IMPORTANT
Science for Class 7 - Part 1>Chapter 3 - Acids and Alkalis>Exercise 4>Q 2

Just as you prepared hibiscus paper, you can prepare similar papers by rubbing different substances on white paper. What are the substances that can be used?