NCERT Class 6 Science Chapter 6 Changes Around us Activity Solution
This activity asks us to inflate a balloon and see if we can reverse the things.
Answer: We can inflate or deflate on our wish. It is reversible.
This activity asks us to make a paper aeroplane by folding it and see if we can reverse the things.
Answer: We can make paper aeroplane by folding the paper. We can unfold the aeroplane and get the paper in the previous shape.
The activity 3 ask us to roll a roti from the dough and check if we can make the dough again if we are not happy with the rolled roti.
Answer: We can roll the dough into roti and can reverse the thing as well.
The activity 4 asks us to prick the balloon and see if we can get back the balloon in the previous shape.
Answer: Pricking an inflated balloon is irreversible. Here we cannot get back the balloon in the previous state.
The activity 5 asks us to draw an aeroplane on paper, cut it and see we can get back the paper in the original state.
Answer: Once we cut the paper we cannot get back the paper in the original state.
the activity asks us to bake a rolled roti on tava and see if we can get back the dough.
Answer: Baking of rolled roti is irreversible. Here we cannot get the dough we used to make roti.
Inference of activities one to six
Some processes are reversible while some are not.
Examples of reversible things mentioned in this chapter:
Clay lump to pot, wet cloth to dry cloth, woollen yarn to a knitted sweater, cold milk to hot milk, straight string to coiled string, stretched rubber band to its normal size, ice cream to molten ice cream, heating wax.
Examples of irreversible things mentioned in this chapter:
Baked clay pot to clay lump, raw egg to boiled egg, batter to idli, grain to its flour, bud to flower, milk to paneer, cow dung to biogas, black tar to a road, burning of the candle, burning of an incense stick, milk to curd.
Activity 7 asks us to burn a candle and incense stick and see if we can reverse the thing.
Answer: Burning of a candle or incense stick is irreversible, we can not reverse it.