Question

Which of the following statements is incorrect? The members of the homologous series of alkanes:
A. are all straight-chain compounds
B. has the general formula \[{C_n}{H_{2n + 2}}\]
C. have similar chemical properties
D. shows a regular gradation of physical properties

Answer 1

Hint: Alkanes are saturated hydrocarbons. That means that the hydrocarbon (molecules containing only hydrogen and carbon) has only single bonds and that the hydrocarbon contains the maximum number of hydrogen atoms for each carbon atom. For example, methane.

Complete step by step answer:
The general formula of the alkanes is \[{C_n}{H_{2n + 2}}\] .
All the alkanes compounds of homologous series show similar chemical properties. Alkanes also shows a regular gradient of physical properties.
But alkanes can be straight-chain as well as branched, cyclic, etc. but they should be different by \[ - C{H_2}\] the unit. Some structures of alkanes are shown below.

So, the correct option is A.

Additional information:
Cycloalkanes are alkanes with ring structures. There are some examples like, in case of hexane there are six carbons in a chain, but in case of cyclohexane there are six carbons form a hexagonal ring of six carbon members. The structures are shown below.


Note: Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. Now, the term unsaturated (not saturated) means that more hydrogen atoms may be added to the hydrocarbon to make it saturated (i.e. consisting of all single bonds).
All the hydrocarbons containing the “ane” suffix contain a single bond between the carbon atoms whereas those containing the “ene” suffix contain a double bond between carbon atoms and those having the “one” suffix contain a triple bond between carbon atoms.