Option 1, CH3(CH2)12COOCH3, is the chemical formula for a common type of ester, methyl laurate. Esters are not typically used as soap, as they do not have the necessary properties for cleaning.

Option 2, CH3(CH2)50(CH2}5CH3, is a very long chain of carbon atoms. This compound is an example of a hydrocarbon and is not commonly used as soap either. Hydrocarbons do not have the ability to dissolve in water, which is an important property of soap.

Option 3, CH3(CH2)12COONa, is the chemical formula for sodium laurate. This compound is a type of soap because it contains a long hydrocarbon chain (CH3(CH2)12) and a sodium ion (Na+). The sodium ion allows the compound to dissolve in water, making it suitable for cleaning.

Option 4, CH3(CH2)12CHC12, is the chemical formula for 1-dodecyl-1-chloroethane. This compound is not commonly used as soap, as it is a chlorinated hydrocarbon and does not have the necessary properties for cleaning.

Therefore, option 3, CH3(CH