Question

Which of the following is not a physical change?
(A)- Melting of wax
(B)- Tearing a piece of paper
(C)- Cutting wood
(D)- Digestion of food

Answer 1

Hint: Physical changes are described as those changes which are visible through the eyes directly. And they are characterized by changing the size or shape and sometimes the state of matter also, but their chemical properties never get changed.

Complete answer:
 Now we will discuss the above-given options in the following manner:
-In option (A) melting of ice is given, which is a physical change because due to heat solid-state of wax gets converted into melted form but the chemical property of wax is not changed during this conversion.
-In option (B) tearing a piece of paper is given, which is also an example of physical change because of the size of the original paper changes after tearing.
-In option (C) cutting of wood is given, which is obviously a physical change as the shape and size of wood gets altered but its chemical property remains conserved.
-In option (D) digestion of food is given, which is a chemical change as after digestion of food all the properties of injected food and digested food gets changed and it is also not visible to our eyes.
From the above discussion, it is clear that digestion of food is not a physical change. So, the correct answer is “Option D”.

Note: Here some of you may think that during digestion of food also the state of food changes then why it will not come under the category of physical change, so the reason is that during physical change the only state will change but chemical properties will remain unchanged. And in the digestion of food with physical properties, chemical properties also get changed that’s why it will come under the category of chemical change.