Write the name and structure of saturated hydrocarbons having 3, 4, 5 and 6 carbon atoms joined in a straight chain.

We first write the required carbon atoms joined together in a chain and then complete the remaining valencies with hydrogen atoms. In this way, we get the following structures for saturated hydrocarbons having 3, 4, 5 and 6 carbon atoms respectively. Then name these according to the number of carbon atoms, e.g., propane, butane, pentane and hexane for saturated hydrocarbons containing 3, 4, 5 and 6 carbon atoms respectively.