It would be A. proton and electron
Answer:

Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to calculate the required grams of HCl by firstly identifying the limiting reactant via the moles of each reactant as they are in a 1:1 mole ratio:

Thus, we infer the hydrogen is the limiting reactant and therefore we use its 1:2 mole ratio with HCl whose molar mass is 36.46 g/mol:

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Answer:
After Eris was discovered, they had to decide whether Eris was a planet or not. If they decided it wasn't a planet, they had to also decide whether Pluto should be counted as a planet since Eris and Pluto were quite similar. They were the same size, and they were both part of the Kuiper Belt.
Explanation:
I think the correct answer from the choices listed above is option D. The correct mass of nitrogen would be 2.9 g. The mass is calculated by multiplying the density and the volume of the substance. The correct answer should have two significant figures since it is the least precise operation.