00:01
Hi there.
00:02
In this question, we are looking for the formula that has the smallest number of hydrogen atoms.
00:17
All right.
00:17
So to do this the most efficient way, it's helpful if we know the general formula for an alkan, a hydrocarbon with all single bonds, an alken, a hydrocarbon with at least one double bond, and an alkyne, a hydrocarbon with one triple bond.
00:36
So an alkan has the general formula c to the n, h to the 2n plus 2.
00:44
Whereas an alken has the general formula c to the n, h to the 2n, and an alkyne has the general formula c to the n, h to the 2n, minus 2.
00:58
Okay, so let's look at each of these options we have.
01:01
We have two methyl propane.
01:07
This is an alcane.
01:08
We know that because it ends with a &e.
01:11
The methyl group means one carbon.
01:14
The probe means three carbons.
01:17
So this whole molecule has four carbons.
01:20
And 2n plus 2 would give us 10 hydrogen.
01:26
Next we have butane.
01:31
So in butane, a &n -e -ending tells us it is an alkan.
01:36
So it is also going to be c4h10...