Question

question 7 (1 point)
which alkane would most likely be a liquid at room temperature?
methane
ethane
propane
butane
pentane
question 8 (1 point)
which feature do all aromatic hydrocarbons have?
an amine group
halogens
a benzene ring structure
an aldehyde group
all double bonds in a ring

Explanation:

Question 7

Alkanes' physical state at room temperature (around \(25^{\circ}C\)) depends on their molecular size. Smaller alkanes (\(C_1 - C_4\)) are gases. Methane (\(CH_4\), \(C_1\)), ethane (\(C_2H_6\), \(C_2\)), propane (\(C_3H_8\), \(C_3\)), and butane (\(C_4H_{10}\), \(C_4\)) are gases. Pentane (\(C_5H_{12}\), \(C_5\)) has a higher molecular weight, stronger London - dispersion forces (due to more electrons and larger surface area for intermolecular interaction), and is a liquid at room temperature.

• An amine group (\(-NH_2\)) is a functional group in amines, not a characteristic of aromatic hydrocarbons.
• Halogens (\(-X\), where \(X = F, Cl, Br, I\)) are substituents in halo - hydrocarbons, not a general feature of aromatic hydrocarbons.
• An aldehyde group (\(-CHO\)) is in aldehydes.
• Aromatic hydrocarbons (by the Hückel's rule, which states that planar, cyclic, conjugated compounds with \(4n + 2\) (\(n=0,1,2,\cdots\)) \(\pi\) - electrons have aromaticity) have a benzene - ring structure (a six - membered ring with three conjugated double bonds). While some non - benzene aromatic compounds exist, the most common and defining feature for the general class of aromatic hydrocarbons taught at an introductory level is the benzene - ring structure. Compounds with “all double bonds in a ring” like cyclobutadiene (\(C_4H_4\), \(4n\) \(\pi\) - electrons, \(n = 1\)) are anti - aromatic (unstable), not aromatic in the traditional sense of aromatic hydrocarbons (which are stable).

Answer:

pentane

Question 8