Final answer:
Class A fire extinguishers are not suitable for flammable liquids or electrical fires; Class B or C extinguishers should be used instead. Water can conduct electricity and worsen an electric fire, hence using a proper extinguisher is critical for safety.
Step-by-step explanation:
Class A fire extinguishers are designed to put out fires involving ordinary combustibles such as wood, paper, and cloth, but they are not suitable for fires involving flammable liquids or electricity. When dealing with flammable liquids, it's essential to use a fire extinguisher that can effectively cover the liquid and prevent the fire from spreading, such as a Class B extinguisher which often uses a foaming agent. Similarly, Class C extinguishers are formulated for electrical fires, which could be exacerbated by water or other conducting media as in Class A extinguishers, due to water's property to conduct electricity. Therefore, one should never throw water on an electric fire.
Furthermore, handling flammable substances requires caution and adherence to safety instructions like keeping them away from heat sources, not flicking electric switches with wet hands to prevent electrical shocks, and knowing the location of fire safety equipment in environments like laboratories.