Of the types of fire extinguishers, what is a soda-acid extinguisher NOT appropriate for?

Soda-acid extinguishers, which are classified as Class A extinguishers, work by utilizing a chemical reaction between sodium bicarbonate (baking soda) and sulfuric acid to produce carbon dioxide, which helps smother the fire. This type of extinguisher is effective for ordinary combustibles, such as wood, paper, and textiles, which is why it is appropriate for wooden furniture fires.

However, soda-acid extinguishers are NOT suitable for fires involving electricity, such as electric motor control fires. This is because they conduct electricity, and using them in such situations may lead to the risk of electric shock or further spreading of the fire. Fire extinguishers designed for electrical fires are usually CO2 or dry chemical extinguishers that do not conduct electricity and can safely handle such scenarios.

When it comes to flammable liquid fires (option C) and gasoline fires (option D), while soda-acid extinguishers may have some limitations, they are not the primary concern compared to their unsuitability for electric fires. In summary, soda-acid extinguishers are not appropriate for fires involving electrical components, indicating why this option is the correct answer.