Matter in Our Surroundings

Que 1. Mrs. Khanna was making breakfast in kitchen. For this purpose she was heating water in a pan. In the meantime, her 12 years old son, Pappu entered the kitchen and saw the water vapour coming out from the pan.

Pretend yourself to be Mrs. Khanna and answer the following questions:

(i) What is the process going on in the pan?

(ii) Why was this process occurring?

(iii) Give one way by which Pappu can relate this phenomenon with his everyday life.

(iv) What values are shown by Pappu? 

Ans.

(i) Evaporation of water.

(ii) The water absorbs heat from the burner and the water molecules keep changing their energies due to molecular collisions as a result of which some molecules at the surface of the liquid acquire sufficient energy and escape.

(iii) During summer season Pappu wears cotton clothes and perspires more. The heat energy required for evaporation is absorbed from the body leaving the body cool. In this way he relates evaporation with his day to day life.

(iv) Curiosity, observatory skills.

Que 2. One day, Reena was helping her mother in household work. Suddenly a bottle from her mother's cosmetics broke and the liquid fell on her hand. She got worried and asked her mother why she felt cold. Her mother explained the reason to her which satisfied her.

Answer the following questions based on above passage. 

(i) Can you guess the liquid that felt on Reena's hand? 

(ii) Why did she feel cold when liquid fall on her hand? 

(iii) What are the values shown by Reena's mother?

Ans.

(i) The liquid is nail paint remover which contains acetone.

(ii) Acetone in nail paint remover is a volatile compound. It evaporates at a high rate and absorbs heat from her hand. So, she felt cold.

(iii) Knowledgeable, educated.