Question

Question #894bd

Answer 1

Consider toluene,

By your notation, and the given molecule, I'm going to assume hydrogens attached to `1°` carbons, et cetera.

`1°` carbons have one other carbon attached, `2°` carbons have two other carbons attached, and `3°` carbons have three other carbons attached.

Hence,

`1°:` 3 hydrogens on the methyl group
`2°:` 5 hydrogens throughout the arene, and
there are no `3°` carbons.

If I'm referring to the wrong concept, I'm open to feedback!