Answer:

Explanation:
Hello!
In this case, when determining empirical formulas by knowing the by-mass percent, we first must assume the percentages as masses so we can compute the moles of each element:

Now, for the determination of the subscript of each element in the empirical formula, we divide the moles by the fewest moles (P or N):

Thus, the empirical formula is:

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Answer (3) is the most correct, although (2) is not to be ignored. (3) states the most abundant isotope Ti's average mass, which is certainly true. (2) is the total mass of all protons, neutrons, and electrons in an atom of Ti, which is true but has to be more specific in order to pinpoint exactly the 47.88 amu. (4) is incorrect because it is not of all the naturally occurring isotopes of Ti. (1) is incorrect because they forgot electrons.
Answer:
In 4.5 grams of tetraphosphorus decoxide we have 3.85 * 10^22 phosphorus atoms
Explanation:
Step 1: Data given
tetraphosphorus decoxide = P4O10
Molar mass of P4O10 = 283.89 g/mol
Mass of P4O10 = 4.5 grams
Number of Avogadro = 6.022 * 10^23 / mol
Step 2: Calculate moles of P4O10
Moles P4O10 = mass P4O10 / molar mass P4O10
Moles P4O10 = 4.5 grams / 283.89 g/mol
Moles = 0.016 moles
Step 3: Calculate moles of P
For 1 mol P4O10 we have 4 moles of phosphorus
For 0.016 moles P4O10 we have 4*0.016 = 0.064 moles P
Step 4: Calculate number of P atoms
Number of P atoms = moles P * number of Avogadro
Number of P atoms = 0.064 moles * 6.022*10^23
Number of P atoms = 3.85 * 10^22 atoms
In 4.5 grams of tetraphosphorus decoxide we have 3.85 * 10^22 phosphorus atoms

Explanation:
the bottom number would be 54. This is because you add one to 53 to make it 54 and you add 0 to 138.