Structures and IUPAC names of some hydrocarbons are given below. Explain why the names given in the parentheses are incorrect.
`underset(["and not 3,4,7-Trimethyloctane"])underset(2,5,6- "Trimethyloctane")(CH_(3)-underset(CH_(3))underset(|)(CH)-CH_(2)-CH_(2)-underset(CH_(3))underset(|)(CH)-underset(CH_(3))underset(|)(CH)-CH_(2)-CH_(3))`
`underset(["and not 5-Ethyl-3-methylheptane"])underset("3-Ethyl-5-methylheptane")(CH_(3)-CH_(2)-underset(CH_(2)CH_(3))underset(|)(CH)-CH_(2)-underset(CH_(3))underset(|)(CH)-CH_(2)-CH_(3))`

Explanation

To determine why the names given in parentheses for the hydrocarbons are incorrect, we need to analyze the structures and apply the IUPAC naming rules.

### Step-by-Step Solution:

1. **Identify the Structures**:
- The first structure is a branched octane with multiple methyl groups.
- The second structure is a heptane with an ethyl and a methyl group.

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