Two of the liquids, n-pentane and 1-butanol, had nearly the same molecular weights, but significantly different ∆t values. explain the difference in ∆t values of these substances, based on their intermolecular forces.

For this item, the ∆t will be the value of temperature difference that the substances will experience once subjected to same amount of heat. The heat is equal to,

    H = mcp∆t

where H is heat, m is mass, cp is specific heat, and ∆t is temperature difference. 

The compounds given, despite having the almost the same molecular weight, will have different ∆t because of the different intermolecular forces present especially in the alkyl groups present.