Question

Alkanes, alkenes, and alkynes are all hydrocarbons. Consider the examples of ethane, ethene, and ethyne. All three types of hydrocarbons have something in common. What is it?A) All three are saturated hydrocarbons.B) They all have the same number of carbon atoms.C) They all have the same number of hydrogen atoms.D) The functional group of all is a carbon-carbon double bond.

Answer 1

First, let's see the structure of each hydrocarbon:

Ethane has the following structure:

We can realize that it contains simple bonds between the two carbon atoms and six hydrogens.

Now, ethene, which you can call ethylene too:

We can realize that it contains a double bond between the two carbon atoms and four hydrogens.

And finally, ethyne has this structure:

In this case, ethyne contains a triple bond between the two carbons and two hydrogens.

The prefix eth- is telling us that we have two carbons in the chemical structure, so the common thing that we can note is that they all have the same number of carbons. All of them contain two carbon atoms, so the answer is B.

Remember that the type of bond, changes the number of hydrogen atoms and the saturated hydrocarbons are those with double or triple bonds between the carbon atoms.