(a) Are you more likely to see the density of a gas reported in $\mathrm{g} / \mathrm{mL}, \mathrm{g} / \mathrm{L},\( or \)\mathrm{kg} / \mathrm{cm}^{3} ?(\mathbf{b})$ Which units are appropriate for expressing atmospheric pressures, $\mathrm{N}, \mathrm{Pa}, \mathrm{atm}, \mathrm{kg} / \mathrm{m}^{2} ?$ (c) Which is most likely to be a gas at room temperature and ordinary atmospheric pressure, $\mathrm{F}_{2}, \mathrm{Br}_{2}, \mathrm{~K}_{2} \mathrm{O} .$

The density of a gas is usually reported in units that take up the lightness and the relatively large volume occupied by gases. The most common units for gas density are grams per liter (g/L) since these units represent the mass of a gas in a large volume. Therefore, the density of a gas is more likely to be reported in g/L.

Atmospheric pressure can be expressed in several units, including Newtons (N), Pascals (Pa), atmospheres (atm), and kg/m². However, some units are more appropriate and commonly used to express atmospheric pressure. Pascals (Pa) and atmospheres (atm) are the most common units to express atmospheric pressure since they directly relate to the force exerted by the atmosphere on a given area. Therefore, Pa and atm are the appropriate units for expressing atmospheric pressure.

To predict which substance will be a gas at room temperature and atmospheric pressure (F2, Br2, or K2O), we should consider the intermolecular forces and the molecular weight of each substance. 1. F2 (Fluorine) is a diatomic gas, and Halogens (group 17 elements) have weak London dispersion forces between their molecules. F2 has the lowest molecular weight among the halogens, making it more likely to be a gas at room temperature. 2. Br2 (Bromine) is also a halogen, but it is a liquid at room temperature due to its heavier molecular weight, which results in stronger London dispersion forces compared to F2. 3. K2O (Potassium Oxide) is an ionic compound composed of potassium and oxygen ions. Ionic compounds have strong electrostatic forces between the ions, which result in high melting and boiling points. Therefore, K2O is most likely to be a solid at room temperature. Taking these factors into consideration, F2 (fluorine) is the most likely to be a gas at room temperature and ordinary atmospheric pressure.