Final answer:
Methanol has a higher melting point than ethane because it can form strong hydrogen bonds due to the presence of a hydroxyl group, while ethane can exhibit only weaker dispersion forces.
Step-by-step explanation:
Melting Point Comparison of Methanol and Ethane
The melting point of a compound is significantly influenced by the types of intermolecular forces present within the substance. In comparing methanol (CH_3OH) and ethane (C_2H_6), we must consider the molecular structure and the intermolecular forces that each of these compounds can exhibit. Methanol has a hydroxyl group (-OH), which makes it capable of forming hydrogen bonds, a type of strong dipole-dipole interaction. On the other hand, ethane is a nonpolar molecule with only carbon-hydrogen bonds, hence only exhibiting weaker London dispersion forces.
Since hydrogen bonding is significantly stronger than London dispersion forces, methanol will have a higher melting point compared to ethane. Therefore, the correct answer is A. CH_3OH because it has a hydrogen directly bonded to an oxygen, allowing for hydrogen bonding which increases the melting point.