A compound with a molecular formula of C₆H₁₄ has two tertiary carbons. Its IUPAC name is :

To determine the IUPAC name of the compound with the molecular formula $C_6{H}_{14}$ that contains two tertiary carbons, let's analyze the structural features step-by-step:

1. Understand the carbon classifications:
- A primary (1°) carbon is bonded to only one other carbon atom.
- A secondary (2°) carbon is bonded to two other carbon atoms.
- A tertiary (3°) carbon is bonded to three other carbon atoms.
- A quaternary (4°) carbon is bonded to four other carbon atoms.

2. Analyze the options and count their tertiary carbons:

Option 1: n-hexane
The structure of n-hexane is:
${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$
This straight-chain alkane contains only primary carbons (the two terminal methyl groups) and secondary carbons (the four internal methylene groups). It has zero tertiary carbons.

Option 2: 2-methylpentane
The structure of 2-methylpentane is:
${\mathrm{CH}}_3-\mathrm{CH}\left({\mathrm{CH}}_3\right)-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$
Here, carbon-2 is bonded to three other carbons (carbon-1, carbon-3, and the methyl branch at carbon-2), making it a tertiary carbon. All other carbons are either primary or secondary. Thus, it contains only one tertiary carbon.

Option 3: 2,3-dimethylbutane
The structure of 2,3-dimethylbutane is:
${\mathrm{CH}}_3-\mathrm{CH}\left({\mathrm{CH}}_3\right)-\mathrm{CH}\left({\mathrm{CH}}_3\right)-{\mathrm{CH}}_3$
Let's look at the carbon skeleton. Carbon-2 is bonded to carbon-1, carbon-3, and the methyl group attached to it (three carbon atoms). Carbon-3 is bonded to carbon-2, carbon-4, and the methyl group attached to it (three carbon atoms). Both carbon-2 and carbon-3 are tertiary carbons. Therefore, this compound has exactly two tertiary carbons, matching the criteria.

Option 4: 2,2-dimethylbutane
The structure of 2,2-dimethylbutane is:
${\mathrm{CH}}_3-C{\left({\mathrm{CH}}_3\right)}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3$
In this molecule, carbon-2 is bonded to four other carbon atoms, making it a quaternary carbon. It contains zero tertiary carbons.

Conclusion:
Only 2,3-dimethylbutane has the molecular formula $C_6{H}_{14}$ and contains exactly two tertiary carbons.