Classify each of the following, as a physical or a chemical change. Give reasons. (a) Drying of a shirt in the sun. (b) Rising of hot air over a radiator. (c) Burning of kerosene in a lantern. (d) Change in the colour of black tea on adding lemon juice to it. (e) Churning of milk cream to get butter.
Answers
Answer:
a Drying of shirt in the sun is a Physical change. Since in this change no new substance is formed.
b Since, in rising of hot air over a radiator no new substance is formed, hence it is a Physical change.
c while burning of kerosene in a lantern carbon dioxide, and water vapour is formed, hence it is a Chemical change.
d In this change a new substance is formed, hence it is a Chemical change.
e While churning of milk cream to get butter, no new substance is formed, hence it is a Physical change.
Explanation:
(a) Drying of a shirt in the sun.
Answer: Drying of shirt in the sun is a Physical change. Since in this change no new substance is formed.
(b) Rising of hot air over a radiator.
Answer: Since, in rising of hot air over a radiator no new substance is formed, hence it is a Physical change.
(c) Burning of kerosene in a lantern.
Answer: While burning of kerosene in a lantern carbon dioxide, and water vapour is formed, hence it is a Chemical change.
(d) Change in the colour of black tea on adding lemon juice to it.
Answer: In this change a new substance is formed, hence it is a Chemical change.
(e) Churning of milk cream to get butter.
Answer: While churning of milk cream to get butter, no new substance is formed, hence it is a Physical change.