MEDIUM
6th CBSE
IMPORTANT
Earn 100

Why are gaps left between rails on a railway track?

Important Questions on Changes Around Us

EASY
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 6
What are reversible and irreversible changes? Give examples.
HARD
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 1
Justify the statement - physical changes can be reversible as well as irreversible.
MEDIUM
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 2
Justify the statement giving examples — heating brings about chemical changes in some substances whereas physical changes in others.
HARD
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 3
Addition of water to salt or sand is a physical change whereas to cement is a chemical change. Justify the statement.
HARD
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 4
Why does a glass tumbler containing hot water crack if we cool it by pouring cold water on it?
MEDIUM
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 5
Have you ever lighted a candle on festivals, birthdays or some other occasions? You must have observed the following when a candle is lighted: 
• Candle burns to produce carbon dioxide, water vapour and light. 
• The size of the candle decreases. 
• Some of the wax melts. 
Now classify the above changes as reversible or irreversible. 
HARD
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 1
Instead of mercury metal can we use copper metal in a thermometer? (Hint: which state, solid or liquid, shows more expansion or contraction on change of temperature) 
HARD
6th CBSE
IMPORTANT
Head Start Science 6>Chapter 6 - Changes Around Us>EXERCISES>Q 2
Sam took out porridge kept in a glass bowl from the refrigerator. As he wanted to have it hot, he put it directly into the microwave oven for heating. To his surprise the glass bowl had cracked!! Can you help him figure out why this had happened?