The correct option for soda-acid fire extinguishers is option-2, Sodium hydrogen carbonate.

In soda-acid fire extinguishers, the extinguishing agent is a solution of sodium hydrogen carbonate (also called baking soda) in water. When mixed with water, sodium hydrogen carbonate produces carbon dioxide gas. This gas is what helps to extinguish the fire.

Option-1, Sodium chloride, is not used in soda-acid fire extinguishers. Sodium chloride is commonly known as table salt and does not have the same fire-extinguishing properties as sodium hydrogen carbonate.

Option-3, Calcium hydroxide, is not used in soda-acid fire extinguishers. Calcium hydroxide, also known as slaked lime or lime water, is used in other applications such as in construction and water treatment.

Option-4, Acetic acid, is not used in soda-acid fire extinguishers. Acetic acid is commonly known as vinegar and is not suitable as a fire extinguishing agent.

Therefore, the correct answer is option-2, Sodium hydrogen carbonate.