Why graphite is a good conductor of electricity, but diamond is a non-conductor of electricity? 

Why does carbon form compounds mainly by covalent bonding? 

State any four properties in which covalent compounds differ from ionic compounds.

Define a functional group. Which of the following pairs have similar chemical properties and why? 

CH₃Cl, CH₂OH;

HCOOH, CH₃CHO       and

C₂H₅OH, CH₃OH. 

What is meant by homologous series of carbon compounds? Classify the following carbon compounds into two homologous series and name them.

${\mathrm{C}}_3{\mathrm{H}}_4, {\mathrm{C}}_3{\mathrm{H}}_6, {\mathrm{C}}_4{\mathrm{H}}_8, {\mathrm{C}}_4{\mathrm{H}}_8, {\mathrm{C}}_5{\mathrm{H}}_8, {\mathrm{C}}_5{\mathrm{H}}_{10}$