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How many molecules are there in 14g of nitrogen gas at s.t.p? (n = 14,...

Chemistry
WAEC 1990

How many molecules are there in 14g of nitrogen gas at s.t.p? (n = 14, Avogadro Number = 6. 0 x \(10^{23 }\)mol-1)

  • A. 1.2 x 10 23
  • B. 3.0 x 1023
  • C. 6.0 x1023
  • D. 1.2 x 1024
  • E. 30 x1023
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Correct Answer: Option B
Explanation

mass of nitrogen gas = 14g, molar mass of nitrogen gas = 28gmol-1

mole = \(\frac{mass}{molar mass} = \frac{ no  of  particles }{ avogadro's no }\)

moles =  \(\frac{14}{28} = \frac{ no  of  particles }{ 6.0 \times 10^{23}}\)

no of molecules = 0.5 x 6.0 x \(10^{23}\)

=  3.0 x \(10^{23}\)molecules.


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