10. O/N 2018/P12/Q34
Which statement about the homologous series of alkanes is correct?
A Alkanes are unsaturated hydrocarbons.
B Alkanes all have the general formula CnH2n.
C The boiling points decrease as the number of carbon atoms per molecule increases.
D The liquid alkanes become more viscous as the mass of the molecules increases.
Answer: D
Explaination
All alkanes are saturated hydrocarbon as they contain only single C-C single bond and C-H single bond. Alkanes have the general formula CnH2n+2, if alkane contains 1 C atom then n=1. It has the molecular formula C(1)H2(1)+1 = CH4. This is methane. Their physical properties gradually increases down the series for boiling point, melting point, viscosity as the C chain grows longer and heavier with increase molecular mass.
