Ans. Esters have a general formula which is RCOOR' where R and R’ belong to alkali groups. We get them through the reaction of acids with alcohols. In case if the Ester is formed from the acid RCOOH and alcohol R’OH then the formula for the Ester will be RCOOR’ which will be followed by the elimination of water molecules. For example, CH3COOCH3 - Methyl ethanoateCH3COOC2H5 - Ethyl ethanoateOne must use the alcohol group first in order to name the esters. In the above case, we first use Ethyl and then use the name of the carboxylic acid with  -oate ending, in this case, ethanoate.Following are a few examples of esters:Ethyl propanoate forms from ethanol and propanoic acid therefore its formula is CH3CH2COOCH2CH3.Propyl methanoate forms from propanol and methanoic acid therefore its formula is -HCOOCH2CH2CH3.