Answer:
D I think the answer is D for this question
<span> The production of absorption and emission lines . The first theory of the atom to provide an explanation of </span>hydrogen's<span> observed </span>spectral lines<span> those two energy levels, the electron </span>can<span> exist only in </span>certain<span> sharply defined . The </span>number<span> of protons in the nucleus of an atom determines the </span>element<span> that </span>
This problem is providing the initial volume and pressure of nitrogen in a piston-cylinder system and asks for the final pressure it will have when the volume increases. At the end, the answer turns out to be 2.90 atm.
<h3>Boyle's law</h3>
In chemistry, gas laws are used so as to understand the volume-pressure-temperature-moles behavior in ideal gases and relate different pairs of variables.
In this case, we focus on the Boyle's law as an inversely proportional relationship between both pressure and volume at constant both temperature and moles:

Thus, we solve for the final pressure by dividing both sides by V2:

Hence, we plug in both the initial pressure and volume and final volume in order to calculate the final pressure:

Learn more about ideal gases: brainly.com/question/8711877
Answer:Iron is extracted from iron ore in a huge container called a blast furnace. Iron ores such as haematite contain iron(III) oxide, Fe 2O 3. The oxygen must be removed from the iron(III) oxide in order to leave the iron behind. Reactions in which oxygen is removed are called reduction reactions.