Hi, Gabrielle,
A) CH3CH2CH2CH3: This is an alkane with 4 carbons and all single bonds with no oxygen or other elements. The prefix for the 4 carbons is but- and the suffix for the alkane is -ane, so the compound is butane.
B) H2C=CHCH2CH3: This is an alkene with four carbons. It has a double bond between two carbons and thus is referred to as an alkene. Its prefix is but- , as above, and the suffix for a double bonded carbon is -ene, so the name is butene.
C) CH triple bond CH: This can be written as HCCH or C2H2. The triple bond is called an alkyne (it has a lot of energy stored in the triple bond). The prefix for two carbons is eth- . Alkynes are given the suffix -yne. Technically, the name is ethyne. But it's common nickname is acetylene, as in the acetylene torch.
D) CH triple bond CCH2CH2CH2CH3: Another alkyne. It has 5 carbons, all in one chain, The prefix for 5 is pent-. Add the suffix for triple bonds (-yne) to yield pentyne. Since the triple bond is on the first carbon, it is more accurately named 1-pentyne.
I hope this helps,
Bob
