Question

The strongest conjugate base results from ……
A formic acid
B benzoic acid
C acetic acid
D acetylene

Answer 1

Hint:
According to the Brosted-lowry acid-base theory, the conjugate base is formed after donation of hydrogen ion from an acid. i.e. the negative charged ion of acid is the conjugate base of that particular acid.

Complete step by step answer:
-The strength of acid plays a vital role in the formation of the conjugate base of that acid. if an acid donates hydrogen ion, then its conjugate base accepts hydrogen ion. Now higher the acidity of the acid lower will be the basicity of the conjugate base and vice-versa.
-Therefore, for a strong acid its corresponding conjugate base is a weak base. And for weak acid, its corresponding conjugate base is a strong base.
-Now the strength of acidity depends upon the different factors, some of those are, for carboxylic acids electron withdrawing effect increases the acidity. On the other hand electronegative sp carbon of acetylene shows acidity. But carboxylic acids are more strong acid then acetylene.
-The weakest acid among the given options is acetylene.
-And its corresponding conjugate base will be strongest among others.

So, the correct option is D.

Note:
Higher the acidity of the acid lower will be the basicity of the conjugate base and vice-versa. For a strong acid its corresponding conjugate base I weak base. And for weak acid, its corresponding conjugate base is a strong base. For carboxylic acids electron withdrawing effect increases the acidity.