Which of the following is not absolutely correct?

Options

A. A general tetrahedral orientation of group and thus, `sp^(3)` hybridization is the rule for the `C` atoms of all alkanes.
B. The `C-H and C-C` bonds have the same general electron distribution, being cyclindrically symmetrical about a line joining the atomic nuclei.
C. All four `H` atoms of methane and all six `H` atoms of ethane are identical.
D. Butane and pentane are examples of straight-chain alkanes.

Answer

D

Explanation

One glance at their three-dimensional model is shows that because of the tetrahedral `C` atoms,their chains are zigzagged and not at all straight. Moreover, on account of practically free rotations about the `C-C` single bounds, chains are further kinkled or twisted.
The better description is unbranched. This means that each `C` atom within the chain is bonded to no more than two other `C` atoms and that unbranched alkanes contain only primary and secondary `C` atoms, Unbranched alkanes used to br called normal alkanes or `n`-alkanes, but this designation is archaic and should not be used now.