Odd one out and why is it the odd one out? 7 & 8 please!!!

answerbacterium;

answer;

-chlorine

explanation;

-toxic industrial chemicals are industrial chemicals that are manufactured, stored, transported, and used throughout the world. toxic industrial chemicals can be in the gas, liquid, or solid state.

-they can be chemical hazards (e.g., carcinogens, reproductive hazards, corrosives, or agents that affect the lungs or blood) or physical hazards (e.g., flammable, combustible, explosive, or reactive).