HARD
Earn 100

Mary lit an incense stick. She sensed a pleasant smell for as long as the stick was burning. The incense stick burnt up completely, leaving some ash behind.

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What can be concluded from Mary’s activity?

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Important Questions on Changes Around Us

MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change

The number of endothermic process/es from the following is _______.

A. I2( g)→2I(g)

B. HCl(g)→H(g)+Cl(g)

C. H2O(l)→H2O(g)

D. C(s)+O2( g)→CO2( g)

E. Dissolution of ammonium chloride in water

EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
What happens to an apple if it is cut and left in the open air? What type of change is this?
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
When a candle is lit, the wax melts. Identify it is a physical or chemical change.
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Differentiate between reversible and irreversible changes.
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Give two examples each to explain the difference between changes that can be reversed and those that cannot be reversed.
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
When wood is kept in contact with water for a long time, it rots. Identify it is a physical or chemical change.
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
When a piece of coal is burnt, it turns to ash. Identify it is a Physical change or Chemical change.
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Following are few examples of changes: 
(a) The spilling of water from a bucket
(b) The burning of a candle
(c) The breaking of a glass bottle
(d) The digestion of food
(e) The melting of an ice cube
Which of the changes listed above can be reversed?
 
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
When the sun shines on a puddle of water, the water evaporates. Identify it is a physical change or chemical change.
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Which of the following is an example of a reversible change?
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change

Can you get back the matchstick from the ash left after it is burnt? Why or why not?

HARD
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Seema bought a new skirt for school. When she came home, she realised that it was too long, so she asked her mother to hem it. What kind of change is this?
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Why cannot permanent change be reversed? When milk is turned into curd, its taste changes. Why? Can we change the curd back into milk?
MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
 When a whisked egg is heated, it scrambles. Identify it is a physical or chemical change.
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
What do you understand by a reversible change? Give an example.
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Which of the following is an example of irreversible change?
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Is converting wood into sawdust a reversible change? Give a reason in support of your answer.
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
Select the material that undergoes the change.
Boiling an egg.
EASY
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change

Mention if the change is reversible change or irreversible change. 

Making a mistake while knitting a sweater is a _____.

MEDIUM
Science>Chemistry>Changes Around Us>Favourable and Unfavourable Change
When jelly cubes are heated, they melt. Identify it is a physical or chemical change.