Subject Experts Solutions for Chapter: Physical and Chemical Changes, Exercise 3: HOTS AND VALUE BASED QUESTIONS

Suzane took a piece of paper and then folds it into a paper airplane. She throws it at her little brother.
He is a naughty boy and responds by ripping up the paper. Is it a physical change or a chemical change? Give a reason for your answer.
 Ripping up the paper.
 

Suzane took a piece of paper and then folds it into a paper aeroplane. She throws it at her little brother.
He is a naughty boy and responds by ripping up the paper. Which of the following is an example of a physical change? Give reason for your answer.
(b) Folding the paper into an aeroplane.

The gas we use in kitchen is LPG. In the cylinder, it exists as a liquid. When it comes out from the cylinder, it becomes a gas, then it burns. Mention the changes taking place.

What happens when baking soda is treated with vinegar? Give chemical equation.

Three days when it rained continuously, Akash covered his bicycle with a polythene sheet, whereas his friends just did not bother to do the same to their cycles! Few days later Akash’s friends noticed that their cycles had some brown powdery patches on it where Akash’s seemed to be new.
(a) What quality did Akash exhibit by covering his bicycle?

Three days when it rained continuously, Akash covered his bicycle with a polythene sheet, whereas his friends just did not bother to do the same to their cycles! Few days later Akash’s friends noticed that their cycles had some brown powdery patches on it where Akash’s seemed to be new.

(b) Which metal is used in making a bicycle? What happened to Akash’s friend’s bicycle? Why did the metal develop reddish-brown patches?

Write the chemical name and chemical formula of the following:
(a) Lime Water
(b) Milk of Magnesia
(c) Rust
(d) Blue Vitriol
(e) Baking soda