Write the names of the following compounds:
$(a)$ $CH_3-CH_2-CH_2-CH_2-COOH$
$(b)$ $CH_3-CH_2-C \equiv CH$

Which compound has the molecular formula $CH_{3}CHO$?

Name the functional group of the following compounds:
$(i) \ R-COOH$
$(ii) \ R-COOR'$
$(iii) \ R-OH$
$(iv) \ R-X$

How would you name the following compounds?
$(i)$ $CH_3-CH_2-Br$
$(ii)$ $H-CHO$
$(iii)$ $CH_3-CH_2-CH_2-CH_2-C \equiv CH$

Which of the following are correct structural isomers of butane $(C_4H_{10})$?
$(i)$ $n$-butane: $CH_3-CH_2-CH_2-CH_3$
(ii) Isobutane ($2$-methylpropane): $CH_3-CH(CH_3)-CH_3$
(iii) Cyclobutane: $A$ four-carbon ring structure $(C_4H_8)$
(iv) Ethane dimer: Not a valid isomer of butane.

Why are homologous series of carbon compounds so called? Write the chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their $(i)$ physical properties,and (ii) chemical properties.