Which of the following cannot be used to increase the number of carbon atoms in an organic compound?

In which of the following compounds is the numbering of carbon atoms in the chain correct?

Which of the following substances cannot be used for the replacement of -OH group in organic compound by CI ?

With increase in number of carbon atoms in alkanes, heat of combustion

In which of the following compounds the oxidation number of carbon is maximum

Which of the following contains largest number of carbon atoms ?