Available Answers

1. 1.

   Some common changes are given in the following table. Which of these changes do you think can be reversed?

   S.No.	Changes	Can be reversed Yes/No
   1.	Raw egg to boiled egg
   2.	Batter to idli
   3.	Wet clothes to dry clothes
   4.	Woollen yarn to knitted sweater
   5.	Ripening of a fruit
   6.	Grain to its flour
   7.	Cold milk to hot milk
   8.	Straight string to a coiled string
   9.	Bud to flower
   10.	Milk to paneer
   11.	Cow dung to biogas
   12.	Stretched rubber band to its normal size
   13.	Melting of ice cream

    

2. 2.

   1. Which of the following is/are natural change (s)?
      1. formation of glaciers
      2. weathering of rocks
      3. ripening of fruits
      4. all of these
   2. Melting of ice is a _______________ change.
      1. reversible
      2. irreversible
      3. chemical
      4. none of these
3. 3.

   Tick (√) the correct options:

   1. How do changes occur?
      1. by cooling
      2. by heating
      3. by applying pressure
      4. all of these
   2. When does an object expand?
      1. on cooling
      2. on heating
      3. on applying pressure
      4. all of these
4. 4.

   Tick (√) the correct options:

   1. Burning of coal is a/an _______________ change.
      1. reversible
      2. irreversible
      3. natural
      4. quick
   2. Which of the following is not an irreversible change?
      1. ripening of fruits
      2. baking of cake
      3. blooming of flowers
      4. contraction of metals
   3. Occurrence of day and night is an example of _______________.
      1. change caused by mixing
      2. natural change
      3. human-made change
      4. artificial change
   4. When we apply force on the spring by hanging a weight, the length of the spring _______________.
      1. increases
      2. decreases
      3. remains the same
      4. gets halved
   5. We add a spoonful of _______________ in warm milk to obtain curd.
      1. cold milk
      2. sugar
      3. honey
      4. curd
   6. Formation of glacier is an example of _______________.
      1. human-made change
      2. natural change
      3. human-made and reversible change
      4. natural and irreversible change
   7. When ice melts to water, a change occurs in its _______________.
      1. colour
      2. state
      3. position
      4. composition
   8. Which of the following is a reversible change?
      1. water changing into ice
      2. iron nails becoming rusty
      3. burning of paper to form ash
      4. seed growing into seedling
5. 5.

   Fill in the blanks:

   1. The changes that can be reversed are called _______________ changes.
   2. Objects become _______________ on cooling.
   3. When a combustible substance is heated, it starts _______________.
   4. _______________ causes water to change into steam.
   5. Beating of heart is an example of _______________ change.
   6. Materials _______________ on heating and on cooling.
   7. Stretching of spring is a _______________ change.
6. 6.

   Match the following:

   Column A	Column B
   1. Grinding wheat to flour	(a) reversible change
   2. Cooling or heating	(b) irreversible change
   3. Fixing of iron rim on wooden wheel	(c) natural change
   4. Stretching of rubber band	(d) change in state
   5. Flowering in plants	(e) takes place due to expansion and contraction