Can you help me with 4? Can you give me a rule to follow when naming these?

Answer:
2,2 dimethyl propane
Step-by-step explanation:
To name such an organic compound, first identify the longest carbon chain in the provided table, the fourth compound, its longest carbon chain has three carbon atoms thus, the prefix prop-
Then we find the other substituents attached to the carbon chain. In the given compound it has two methyl (CHβ) groups attached to the second carbon atom.
thus 2,2 since there are two attached.