I had to look for the options and here is my answer:
The two requirements for nuclear fusion that are needed to be met in order for the elements hydrogen and helium fuse to make heavier elements are extremely high temperatures and density. Hope this helps.
Answer:
They have similar properties, because they share similar amounts of electrons in their outer shell, valence electrons! This means they will only be able to interact with other elements with those electrons so they often show similar properties.
Explanation:
Gases have high kinetic energy: the molecules are moving much more than in a liquid or solid. You can cut out A and B. In the liquids, the difference is temperature. If a lower temperature is closer to being solid, and a solid has lower kinetic energy than a liquid, then C is the answer. Hope this helps.
Arrhenius is a substance that dissociates in water to produce hydrogen ions (H+) and there is a clear answer which coincides with this definition. The correct answer is definitely b. a substance that increases the concentration of hydronium ions when dissolved in water.