Answer:
The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. The mass number is different for each different isotope of a chemical element.
Answer:

Explanation:
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In this case, we first apply the ideal gas equation to compute the moles of produced chlorine:

Then, by considering the given reaction, applying the stoichiometry, that shows a 1 to 1 relationship between chlorine and manganese dioxide, we find:

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The answer is the trachea