Draw the products of claisen condensation of (a) ethyl propanoate; (b) ethyl-3-methylbutanoate; (c) ethyl pentanoate. for each, the base used is sodium ethoxide and the solvent is ethanol.

Structures of products has been shown below

Explanation:

In claisen condensation, two ester molecules combines with each other through nucleophilic acyl substitution resulting formation of a -ketoester.At first, one ester molecule gets deprotonated in presence of a strong base e.g. NaOEt yielding a carbanion.The carbanion then gives nucleophilic acyl substitution reaction with another ester molecule to replace alkoxy group present in ester groupGeneral reaction mechanism of claisen condensation along with products of given esters are shown below.

D-no effect on the rate

The mass has escaped into a gas which you can not see so the law stays true.