Answer:
It is less dense than oxygen gas.
Explanation:
Density is a physical property. Reactivity, flammability, and acid compounds are all chemical properties.
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Answer:

Explanation:
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In this case, given the change in volume and pressure of the gas, it is possible for us to recall the Boyle's law as way to understand the inversely proportional relationship between pressure and volume:

Thus, when solving for the final pressure, P2, given the initial pressure and volume and the final volume, we obtain:

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Then as the electrons in the atoms fall back down, they emit electromagnetic radiation (light). The amount of light emitted at different wavelengths, called the emission spectrum, is shown for a discharge tube filled with hydrogen gas in Figure 12.6 below.