NCERT Solutions for Chapter: Physical and Chemical Changes, Exercise 1: Exercise

An iron rod is heated till it becomes red-hot.

Is heating of the iron rod a chemical change? Select the correct response with explanation.

Which of these is a physical change?

Iron gates are coated with a layer of zinc to protect them from rusting. Which components in the air cause rusting?

Ramesh describes how roti is made in his house in 5 steps. Here are the 5 steps:

i). Wheat grains are ground to make flour.

ii). Flour is mixed with water to make soft dough.

iii). Small balls of dough are flattened out with a rolling pin.

iv). The flat round dough is cooked on a pan.

v). The crisp roti is coated with a layer of butter.

In which of the above steps does a physical change take place and in which one does a chemical change take place?

Which of these can never happen in a physical change?

What is the observation in the test tube? Give reasons.

You have dissolved a half teaspoonful of salt in half a glass of water. Will you be able to get the salt crystals from the solution? Write yes or no. Give reasons for your answer.

Asha's mother asked her daughter Asha to boil milk and after some time, she told Usha, Asha's sister, to add a little curd in the same lukewarm milk. Next day, their father, while teaching 'transformation of matter' to his daughters wanted to relate the given activity. So, he asked them 'what type of change was involved in the activity. So, he asked them, 'what type of change was involved in the activities performed by you yesterday?' Predict the answer given by them and justify.