First structure is CH₃-CH₃. It is an alkane with two carbon atoms hence it is called ethane.
Second structure is CH₃-CH₂-CH₂-CH₃. It is an alkane with four carbon atoms hence it is called butane.
Third structure is CH₄. It is an alkane with one carbon atom hence it is called methane.
Fourth structure is CH₃-CH₂-CH₃. It is an alkane with three carbon atoms hence it is called propane.
Answer: 
Explanation:Bond energy of H-H is 436.4 kJ/mole
Bond energy of C-H is 414 kJ/mol
Bond energy of C=C is 620 kJ/mol
Bond energy of C≡C is 835 kJ/mol

= {1B.E(C≡C)+2B.E(C-H) +1B.E(H-H)} - {1B.E(C=C)+4B.E(C-H)}


Answer:
melting
Explanation:
liquid is a good conductor of electricity