Which among the following compounds has highest melting point?

Instantaneous rate of a reaction is $$ - {1 \over 2}{{d[x]} \over {dt}} = - {{d[y]} \over {dt}} = {1 \over 2}{{d[z]} \over {dt}}$$, identify the reaction.

Which of the following reactions shows work of compression?

Identify total number carbon atoms present in undecane.