What are Stars Made Of? Stellar Chemical Composition Quiz

If the universe was created with a large amount of light elements, then stars would primarily be made of those materials. If observation shows that ~73% of the Sun's mass is Hydrogen and ~25% is Helium, then these two dominate. Therefore, Hydrogen and Helium are the primary components.

If a star is powered by nuclear fusion, then it is constantly converting Hydrogen into Helium. If Hydrogen is consumed and Helium is created as a byproduct, then the concentration of Helium must go up over time. Therefore, the statement is true.

If every element absorbs or emits light at specific, unique wavelengths, then it leaves a "fingerprint" in the light spectrum. If we use a spectroscope to see these dark or bright lines, then we can identify which elements are present in the star. Therefore, spectroscopy is the method used.

If a star's core has extreme heat and pressure, then atoms are forced together. If Hydrogen nuclei (protons) join to form Helium, then energy is released. Therefore, this process is nuclear fusion.

If Hydrogen and Helium make up about 98% of a star's mass, then everything else must fit into the remaining 2%. If astronomers call all elements heavier than Helium "metals," then the metallicity of a star is relatively low. Therefore, 2% is the correct estimate.

If the Big Bang occurred, then it produced a massive amount of Hydrogen and Helium in the first few minutes. If stars only created a portion of the total Helium through fusion, then a large "primordial" amount already existed. Therefore, the statement is false.

If a star has more heavy elements like Iron or Magnesium, then there are more atoms available to absorb specific wavelengths of light. If more light is absorbed, then the dark lines in the spectrum become more numerous and intense. Therefore, high metallicity leads to more complex absorption patterns.

If "nucleo" refers to the nucleus and "synthesis" refers to making something, then the word describes the building of atoms. If this happens in the Big Bang (primordial) or stars (stellar), then it covers all element creation. Therefore, the answer is nucleosynthesis.

If the astronomical definition of a "metal" is any element heavier than Helium, then Oxygen, Iron, and Carbon qualify. If Hydrogen and Helium are the two lightest elements, then they are not metals in this context. Therefore, A, B, and D are the correct choices.

If fusing elements creates energy, the star remains stable. If fusing Iron requires more energy than it releases, then the energy production stops. If the core becomes mostly Iron, the star will eventually collapse and explode. Therefore, Iron is the final fusion product.

If Population II stars are old and metal-poor, then Population I stars are younger and formed from gas enriched by previous supernovas. If the Sun contains about 2% heavy elements, then it is a metal-rich, younger star. Therefore, it is classified as Population I.

If Big Bang models predict that the universe should be roughly 75% Hydrogen and 25% Helium by mass, then we look for evidence. If we observe this exact 3:1 ratio in the oldest gas clouds, then the theory is confirmed. Therefore, it is strong evidence for the Big Bang.

If light is separated into its component colors, then we see a unique pattern of lines. If this pattern tells us what the star is made of, then it acts as an ID card. Therefore, the result is a spectrum.

If Hydrogen atoms require a certain energy to show spectral lines, then temperature matters. If the star is so hot that Helium (which is harder to excite) shows strong lines, then the energy levels are very high. Therefore, strong Helium lines often indicate a very hot star.

If the Sun is a main-sequence star, it is mostly H and He. If fusion is happening in the core, the H is slowly turning into He. If Iron is only a tiny trace element, then it is not 50%. Therefore, A, B, and D are correct.

If massive stars burn through their Hydrogen fuel faster than small stars, then they leave the main sequence earlier. If we look at which stars are still "alive" in a cluster and check their metal content, then we can calculate the age. Therefore, composition and mass are key dating tools.

If the Big Bang only made H and He, then the other elements had to come from somewhere else. If previous massive stars exploded as supernovas and scattered heavy elements into space, then new stars (like the Sun) formed from that "dirty" gas. Therefore, the Sun's metals are recycled material.

If we want to rank stars by how many heavy elements they have, then we need a scale. If this scale measures the fraction of mass that is not H or He, then it describes the "metal-ness." Therefore, the term is metallicity.

If a star has almost no metals, then it must have formed very early before other stars had a chance to explode and enrich the gas. If the oldest stars are found in the "halo" or outskirts of the galaxy, then that is the most likely location. Therefore, B is the correct answer.

If fusion only happens in the core, then that is where Hydrogen is turning into Helium. If the outer layers (the surface) do not get hot enough for fusion, then they keep the original recipe of the gas cloud the star formed from. Therefore, the core's composition changes while the surface stays relatively the same.