Question

What similarity is there between a straight-chain four-carbon alkane and alkyne?

Answer 1

Both have a geometric shape that is basically a straight line. A `180^o` shape.

Explanation:

alkyne has a double bond between two of its carbons. If the double bonds is in the 1 or 3 positions then there are two carbons in a chain beyond the double bond. A two carbon chain can not branch (there are not enough carbons) so it is a straight line.

If the double bond is between the second and third carbons then there is a one carbon "chain" at either end of the double bond. This arrangement also results in a straight line

This all assumes a 4 carbon alkyne

Answer 2

About the only similarity is that they are both hydrocarbons — they consist of only carbon and hydrogen.

Explanation:

The only straight-chain alkane is butane, `"CH"_3"CH"_2"CH"_2"CH"_3`.

The two straight-chain alkynes are but-1-yne, `"CH"_3"CH"_2"-C≡C-H"` and but-2-yne, `"CH"_3"-C≡C-CH"_3`

The `"C-C-C"` bond angles in butane are 109.5°, while the `"C-C≡C-H"` and `"C-C≡C-C"` bond angles are all 180°.