What happens when magnesium ribbon burns in air?

Important Questions on Physical and Chemical Changes

MEDIUM

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 8

What is the process of crystallisation? State one of its uses.

HARD

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 1

Write a short note on compounds.

HARD

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 2

What are the rules for writing chemical equations?

HARD

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 3

Discuss chemical equations in detail. Give an example of a word equation.

HARD

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 4

With the help of an activity, show that colour change takes place during a chemical reaction.

MEDIUM

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 5

How will you test for the presence of carbon dioxide release during a chemical reaction?

HARD

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 1

When solid sulphur melts into liquid sulphur, a colour change occurs. The chemical composition of sulphur remains the same before and after the change. Is this a chemical or a physical change?

HARD

7th CBSE

IMPORTANT

Sciwise - A coursebook of Science>Chapter 7 - Physical and Chemical Changes>EXERCISE>Q 2

After burning a magnesium ribbon, ash A is collected. On dissolving substance A in water a solution B is formed. Write the name of substances A and B.