Question

Did I correctly draw 5-butyl-8-ethyl-2,2-dimethyldecane?

Answer 1

You drew 8-ethyl-2,2-dimethyl-5-propyldecane.

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The propyl fragment has three carbons, but on carbon-5, a butyl fragment has four carbons. Otherwise, I think you have it correct. Decane has 10 carbons, and the carbon indexing is consistent with counting from the right-hand side leftwards.

As an exercise, try drawing:

5-butyl-8-ethyl-2,4-dimethyldecane

Check by looking here, but ignore the `R//S` part of the name. (I assume you haven't learned stereochemistry yet.)