Question

Statement 1: The burning of a piece of paper is a physical change.
Statement 2: Once burned, the chemical properties of the paper remain the same.
A. Statement 1 and Statement 2 are correct and statement 2 is the correct explanation of statement 1.
B. Both the Statement 1 and Statement 2 are correct and statement 2 is not the correct explanation of statement 1.
C. Statement 1 is correct but Statement 2 is not correct.
D. Statement 1 is not correct but Statement 2 is correct.
E. Both the Statement 1 and Statement 2 are not correct.

Answer 1

Hint – We will start this question by writing down the given statements. Then we will explain physical and chemical change and what happens during these changes. After explaining these changes, we will relate both the statements with these changes which will give the correct answer.

Complete step-by-step answer:
We know that when the substance undergoes a physical change it remains same after the change, as its chemistry remains same, i.e., its chemical composition remains same. The only change that occurs to it is the change in its size, shape, colour or its state (solid, liquid or gas). Also the physical changes may be reversible.

When a substance undergoes a chemical change its whole chemical composition is changed, as when a chemical change occurs, a chemical reaction takes place, in which we have some reactants undergo chemical change to produce products, which always have a different chemical composition from that of the reactants.

Now, we will discuss the burning of a piece of paper.
When we burn a piece of paper it undergoes a chemical change. During this chemical change, a chemical reaction takes place which burns out the whole piece of paper and leaves a residue called ‘ash’ with some other products such as carbon dioxide in the form of gas and water vapours.
Now, if we take carbon dioxide, water vapours and ash and try to react them to get back the piece of paper, i.e., if we want to reverse the whole reaction, which is not possible because chemical reactions are not reversible.

From the above discussion we can say that burning of paper is not a physical change and also that after a chemical change the chemical composition does not remain the same.
Hence, both the Statement 1 and Statement 2 are not correct.
Therefore, option E is the right answer.

Note – Physical changes are those changes in which the physical properties of the substance are changed. No new substances are formed in these changes and are sometimes reversible. A chemical change occurs when one set of substances change into another new substance which has a new set of properties.