Which of the following is an isomer of compound $(1)$?
$(1) \ CH_3CH_2CHO$
$(2) \ CH_3COCH_3$
$(3) \ CH_3CH=CHOH$
$(4) \ \text{2-methyloxirane (propylene oxide)}$

$C_6H_5C \equiv N$ and $C_6H_5N \equiv C$ exhibit which type of isomerism?

How many structural isomers are possible for the molecular formula $C_4H_{10}O$?

Select the correct pair.

Provide the structures and names of the chain isomers of the molecular formula $C_6H_{14}$ that contain only a methyl group as a substituent.

Identify the pairs of compounds that represent position isomerism.
$(I)$ $CH_3-CH_2-CH_2-CH_2-OH$
$(II)$ $CH_3-CH_2-CH(OH)-CH_3$
$(III)$ $CH_3-C(OH)(CH_3)-CH_3$
$(IV)$ $CH_3-CH(CH_3)-CH_2-OH$
$(V)$ $CH_3-CH_2-O-CH_2-CH_3$
$(VI)$ $CH_3-O-CH_2-CH_2-CH_3$
$(VII)$ $CH_3-O-CH(CH_3)-CH_3$