Which has the greatest number of molecules?
A)28 g of nitrogen,
B)32 g of oxygen,
C)32 g of methane, C
D)38 g of fluorine,

Question

Which has the greatest number of molecules?
A)28 g of nitrogen, 
B)32 g of oxygen, 
C)32 g of methane, C 
D)38 g of fluorine,

Quizplus · Accepted Answer

The number of molecules in a substance is determined by Avogadro's number, which is the number of molecules in one mole of a substance. To find the number of moles in each substance, we divide the given mass by the molar mass (the mass of one mole of that substance). 
A. Nitrogen has a molar mass of 28 g/mol, so 28 g of nitrogen is equal to one mole. Therefore, there are Avogadro's Number of molecules in 28 g of nitrogen.
B. Oxygen has a molar mass of 32 g/mol, so 32 g of oxygen is equal to one mole. Therefore, there are Avogadro's Number of molecules in 32 g of oxygen.
C. Methane (CH4) has a molar mass of 16 g/mol. Therefore, 32 g of methane is equal to 2 moles of methane, which is 2 x Avogadro's Number of molecules.
D. Fluorine has a molar mass of 38 g/mol, so 38 g of fluorine is equal to one mole. Therefore, there are Avogadro's Number of molecules in 38 g of fluorine.
Thus, option C has the greatest number of molecules as it has 2 moles of methane.

Which Has the Greatest Number of Molecules