1 . FILL IN THE BLANKS
1 change is generally reversible .
2 Brownish film on iron object kept in open air is called .
3 Chemical change involves formation of .
4 is formed in burning of magnesium
5 Presence of & are necessary for rusting.
6 water makes the process of rusting fast.
7 Rusting can be prevented by & .
8 Chemical name of baking soda
9 gas turns lime water milky due to the formation of .
10 Physical change involves only change in properties like & .
3 chemical reaction
- Define between physical and chemical change
- Give reason
1 It is dangerous to look for long time at burning magnesium
2 Why magnesium oxide turn litmus paper blue
3 Stainless steel doesn’t rust .
4 Rusting of iron object is faster in coastal areas then desert areas
5 . What happens when :-
1 Magnesium air is burnt in air
2 A nail is added to blue colour copper sulphate solutions
3 Carbon dioxide is passes through lime water
4 Vinegar is added to baking soda
5 Lemon juice is added to baking soda
- Classify the following as physical and chemical change
1 explosion of firework
2 sugar in water
4 melting of wax
5 burning of candle
6 digestion of food
8 burning of coal
9 tearing of paper
10 making aluminum foil
- Mention changes observed during chemical change other than formation of new substance
- Describe how crystals of copper sulphate is formed