Answer
a) 2-methylbutanol
b) butylamine
c) Pentanal
d) Cyclopentanone
e) 2-methoxybutane
f) 2,2-dimethylpropanoic acid
Work Step by Step
a) Count the C in straight chain. Here, it is 4. i.e. word root is 'but'. Now, the main functional group present here is 'OH'. the ending name will be 'anol'. Now, numbering the C in straight chain from 1 to 4 so that the C associated with main functional group gets the minimum number (Numbering is done from the right side). Now, one '$CH_{3}$ group is present at C2 Carbon. Hence, '2-methyl' is added before word root. So, the complete name is 2-methylbutanol'.
b) Number of C in straight chain = 4. hence, the word root is 'but'. $NH_{2}$ group is present i.e. the ending name is amine. Now, add 'yl' after 'but' so, we get the name 'butylamine'.
c) Number of C in straight chain = 5. hence, word root is 'pent'. Find the main functional group. here, it is $-CHO$. i.e. the ending name is 'anal'. C in CHO group always gets number 1 while numbering the C atoms. Hence, the name is 'pentanal'.
d) This is a cyclic compound having 5 C in the ring. Hence, the word root is 'cyclopent'. Now, ketone functional group $-CO-$ is present at C1 position. Hence, ending name is 'anone'. So, the complete name is cyclopentanone.
e) Number of C in straight chain = 4. Hence, word root is 'but'. Now, one $-OCH_{3}$ group i.e. methoxy group is present as a substituent at C2 position if we numbering the C in straight chain from right terminal side. Hence, '2-methoxy' is added before word root. ending name is 'ane' for alkane. hence , the complete name is 2-methoxybutane.
f) Number of C in straight chain = 3. hence, word root is 'prop'. Main functional group here is $-COOH$ at C1 position. hence, ending name is 'anoic acid'. Now, two methyl groups are present at C2 Carbon atom if we numbering the C in straight chain from right terminal side. So, we add '2,2-dimethyl' before word root. so, the complete name is 2,2-dimethylpropanoic acid.
