Hydrogen is the lightest of all \( { }^{1} \mathrm{H} \) elements. Which of these describes this element at room temperature and under standard pressure conditions? Hydrogen is an odorless, colorless, gas. Hydrogen is an odorless, blue-colored, solid.

To determine the correct description of hydrogen (\( { }^{1} \mathrm{H} \)) at room temperature and under standard pressure conditions, we need to consider the physical properties of hydrogen. 1. **State of Matter**: At room temperature (approximately 20-25°C) and standard pressure (1 atm), hydrogen exists as a gas. 2. **Color and Odor**: Hydrogen gas is known to be colorless and odorless. Based on these properties, the correct description of hydrogen at room temperature and under standard pressure conditions is: **Hydrogen is an odorless, colorless gas.** The other option, stating that hydrogen is an odorless, blue-colored solid, is incorrect. Hydrogen does not exist as a solid at room temperature and standard pressure; it would require much lower temperatures to solidify.