Answer:
d. 127 g/mol.
Explanation:
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In this case, since we have the amount of molecules of this this compound, we are able to compute the moles out there by using the Avogadro's number:

Which correspond to the moles of X2. Then, by using the mass we are able to compute the molar mass of X2:

It means that the atomic mass of X halves the molar mass of X2, which is then d. 127 g/mol.
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Answer:
D. 5 moles
Explanation:
C3H8 + 5O2 → 4H2O + 3CO2
5 mol 3 mol
So, to make 3 mol CO2 5 mol O2 are needed.
Answer: 4.1 g of barium precipitated.
Explanation:
According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number
of particles.
To calculate the moles, we use the equation:
Given : moles of barium = 0.030
Molar mass of barium = 137 g/mol
x= 4.1 g
Thus there are 4.1 g of barium that precipitated.
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Answer:</h3>
12.387 moles
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Explanation:</h3>
We are given;
Temperature of chlorine, T = 120°C
But, K = °C + 273.15
Therefore, T = 393.15 K
Pressure, P = 33.3 Atm
Volume, V = 12 L
We are required to calculate the number of moles of chlorine gas,
To find the number of moles we are going to use the ideal gas equation;
PV = nRT
R is the ideal gas constant, 0.082057 L.atm/mol.K
Therefore, rearranging the formula;
n = PV÷RT
Hence;
n = (33.3 atm × 12 L) ÷ (0.082057 × 393.15 K)
= 12.387 moles
Therefore, the number of moles of chlorine are 12.387 moles