Answer:
Three chemical elements: hydrogen, oxygen, and helium.
The difference between metals and metalloids is: metalloids have properties in between those of the metals and non-metals and are semiconductors.
The periodic table is organized by the elemts atomic number, it goes from the element with the lowest atomic number (which is hydrogen) to the element with the highest atomic number (oganesson)
Explanation:
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The correct answer is A. molecular formula = 2 x empirical formula
The given compound C2H10N2 is the molecular formula because the ratios of the elements are not reduced into lowest terms (empirical formula). To get the empirical formula, the ratios must be reduced to the smallest possible integral ratio which gives CH5N. As a result, the ratio between both formulas is 2.
Answer:

Explanation:
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In this case, considering the given chemical reaction:

Thus, by applying the law of rate proportions, we can write:

Whereas the stoichiometric coefficients of reactants are negative due their disappearance and that of the product is positive due to its appearance. In such a way, when we relate the rate of disappearance of hydrogen gas to the rate of formation of hydrogen iodide, we obtain:

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