Answer
a) p-chlorobenzoic acid
b) 3-ethyl-2-methyl-1-hexanoic acid
c) methanoic acid / formic acid.
Work Step by Step
a) One Cl atom and one COOH group are present in the benzene ring. Now, if only one COOH group is present at the benzene ring, then the name will be benzoic acid. The 'Cl' atom is present at para position to -COOH group. So, the name is p-chlorobenzoic acid.
b) Find the longest straight chain of C atoms which includes the C atom of -COOH group. So, here the no. of C in longest straight chain = 6. so, root name is hex and ending name is anoic acid for -COOH group which is at C1 position. Now, if we numbering the C of straight chain from right to left we see that one ethyl group is present at C3 position and one methyl group is present at C2 position. hence, '3-ethyl-2-methyl' is added before 1-hexanoic acid. so, the complete name is 3-ethyl-2-methyl-1-hexanoic acid.
c) total no. of C in straight chain = 1. hence, root name is 'meth' and there is COOH group present in the compound. So, ending name is anoic acid. hence, the name methanoic acid. Also, it is called formic acid.
