Question

Which of the following contains the least
Number of molecules?
a)4.4g CO2 b)3.4g NH3 c)1.6g CH4 d)3.2g SO2

Answer 1

HEY MATE HOPE IT HELPS U....

THE ANSWER IS 4.

Answer 2

The number of molecules:

• One mole of a substance equals $6.022*10^{23}$ units of that substance (such as atoms, molecules, or ions).
• Avogadro's number or Avogadro's constant is the quantity $6.022*10^{23}$.

To find out the least number of molecules, first, we have to find out the number of moles in each case.

Let us find out the number of moles and molecules in each of the following:

a)4.4g $CO_{2}$:

• Molar mass of  $CO_{2}$ = 12+32 = 44
• Number of moles = Mass/Molar mass
• Number of moles = 4.4/44 = 1/10 = 0.1
• Number of molecules = Number of moles x NA
• Number of molecules = 0.1NA

b)3.4g $NH_{3}$:

• Molar mass of  $NH_{3}$ = 14+3 = 17
• Number of moles = Mass/Molar mass
• Number of moles = 3.4/17 = 1/5 = 0.2
• Number of molecules = Number of moles x NA
• Number of molecules = 0.2NA

c)1.6g $CH_{4}$:

• Molar mass of $CH_{4}$  = 12+4 = 16
• Number of moles = Mass/Molar mass
• Number of moles = 1.6/16 = 1/10 = 0.1
• Number of molecules = Number of moles x NA
• Number of molecules = 0.1NA

d)3.2g $SO_{2}$:

• Molar mass of $SO_{2}$  = 32+32 = 64
• Number of moles = Mass/Molar mass
• Number of moles = 3.2/64 = 0.05
• Number of molecules = Number of moles x NA
• Number of molecules = 0.05NA

As we can see after calculating the number of molecules in each case, the least number is 0.05NA.

So the least number of molecules are in d)3.2g $SO_{2}$.

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