MEDIUM
7th CBSE
IMPORTANT
Earn 100

Write a chemical equation which represents the rusting of iron.

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
Carbon dioxide turns lime water milky. Comment.
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 4
What is the measure that could be adopted to prevent the browning of fruits and vegetables?
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 5
Why is crystallisation considered a much better technique than evaporation to separate a solid from its solution?
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 1
Explain how the crystals of copper sulphate are prepared. Why is sulphuric acid added to the solution?
HARD
7th CBSE
IMPORTANT
WOW! SCIENCE Hands-on Learning in SCIENCE 7>Chapter 7 - Chemical Changes and Reactions>EVALUATE>Q 2
Burning of a candle involves both the physical and chemical changes. Comment.
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.