Question

What are the characteristics of chemical change ?
A. Permanent
B. Formation of new substance
C. Absorption or release of heat, light
D. All of above

Answer 1

Hint: In this question, we have to discuss the chemical change and its few characteristics and identify the correct answer. So firstly, chemical change is a change in which one or more new substances are formed. Examples are burning of any substance and rusting of iron.

Complete step by step answer:
-Permanent: Chemical Change is nothing but a change which has a different chemical composition and cannot be reversed by simple methods. Thus chemical changes are also known as permanent change because it is irreversible.
So, Option (A) is correct
-Formation of new substance : Chemical changes occur when a substance combines with
another to form a new substance , called chemical synthesis or , alternatively chemical decomposition into two or more different substances. These processes are called chemical reactions.
So, Option (B) is Correct.
-Absorption or release of heat, light:
A chemical change is endothermic if heat is absorbed by the system from the surroundings .
In the endothermic process, the system gains heat from the surroundings and so the temperature of the surroundings decreases.
-For Chemical change, an endothermic process is positive because the system is gaining heat.
A chemical Change is exothermic if heat is released by the system into the surroundings.
In an Exothermic process, the surroundings are gaining heat from the system, the temperature of the surroundings increases.
For Chemical change, an exothermic process is negative because the system is losing heat.
So, Option (C) is Correct.
Hence from the above discussion we find out that all the three options are correct .
So, the correct answer is “Option D” all of the above.

Note: To check whether a chemical change has occured first the products are checked , If new products are formed which cannot be converted back to the original product it is a chemical reaction . Apart from this color , odor also changes, there is a change in temperature as well .