What are the cons of chemical reactions?

From the negative effects of chemical reactions is the environmental pollution resulting from the emission of some harmful gases from these chemical reactions. The burning reaction is considered from the reactions that produce a lot of pollutant gases such as Fuel-burning, burning of coal and cellulose fibers.

Explanation:

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e