87. Solving a chemistry problem

7. On the chromatogram of petroleum ether samples, peaks of n-pentane, n-hexane and n-heptane were identified, which have retention times of 115, 233 and 365 s, respectively.
chromatographic conditions: stationary phase - squalane, thermostat t-80 C. Using the tabular data on the Kovacs retention indices, identify the compound whose peaks have retention times of a) 152 s, b) 264 s, c) 309 s.
Sorbate Kovacs Index Sorbate Kovacs Index 2-methylpentane 570.5 3-methylhexane 677.0 2-methylpentane 585.6 3-ethylpentane 688.2 2,2-dimethylbutane 540.1 2,2-dimethylpentane 627.9 2,3-dimethylbutane 569.6 2,3-dimethylpentane 674, 4 2-methylhexane 667.7 2,4-dimethylpentane 631.8 3,3-dimethylpentane 662.8 2,2,3-trimethylbutane 644.6