Question

In a certain change, the color of a substance changed. What reaction might this be?
(A) Chemical combination
(B) Photochemical reaction
(C) Irreversible reaction
(D) Physical change

Answer 1

Hint: Whenever there is an interaction between two or more species in a condition to convert them into different substances or species, this process in chemistry is termed as a reaction. The substances that interact are generally chemical elements.

Complete step by step answer:
- In a reaction, the elements that interact with each other are called reactants, and the substance that is formed after the reaction is called the product. The other chemical entities that are used to speed up the process of reaction are called catalysts.
- Generally, changes in a reaction are of two types: Chemical and Physical. The difference between these two reactions is composition. In a chemical reaction, the composition of the substances changes while in a physical reaction the appearance, smell, and display of the sample gets changed without changing the composition.
- Physical changes are the changes in color, temperature, texture, shape, and change of state.
- Chemical changes occur differently. This chemical change occurs when there is a change in the composition of a substance. It generally occurs when bonds are broken down and new ones are formed. - The indicators of a chemical change are change in temperature, color, odor, or there is a formation of a Precipitate or Bubbles.
Hence we can say that from the given options color of the substances changed in chemical combination or reaction.

Therefore, Option (A) is correct.

Note:
 Although we called these changes physical "reactions," in reality, there is no reaction occurring. For a reaction to occur, change must be in the elemental composition of the substance given in the question.