HARD
7th CBSE
IMPORTANT
Earn 100

Burning of a candle involves both the physical and chemical changes. Comment.

Important Questions on Chemical Changes and Reactions

MEDIUM
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 3
Neutralisation reaction is a chemical change. Explain.
MEDIUM
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 4
Why the rusting of iron is slow in the deserts than in the coastal areas?
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 5
Bubbles are produced when acetic acid is added to sodium bicarbonate. Explain.
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 6
Alloying is a very good method of improving the properties of a metal. Explain by giving a few examples.
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 1
You must have seen that the silver articles, such as silver jewellery, turn black after sometimes. Explain this process. Is it a physical or a chemical change? What can be done to clean the silver articles?
MEDIUM
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 2

Explain why the following is an example of a chemical change: 

Photosynthesis.

MEDIUM
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 2

Explain why the following is the example of a chemical change: 

Rotting of an egg.

HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q a)
Identify the type of chemical reaction given below for a chemical equation:
AgNO3+KCl→AgCl↓+KNO3