Question

How many phosphine molecules are in two moles of phosphine?

• A. $1.807\times {10}^{-24}$ molecules
• B. $3.476\times {10}^{-2}$ molecules
• C. $1.717\times {10}^{-2}$ molecules
• D. $1.204\times {10}^{24}$ molecules
• E. $2.414\times {10}^{-1}$ molecules

Answer 1

The correct option is D $1.204\times {10}^{24}$ molecules

Avogadro's number is $6.02\times {10}^{23}$ molecules/mole.
One mole of phosphine $=6.02\times {10}^{23}$ phosphine molecules.
Two moles of phosphine $=2\times 6.02\times {10}^{23}=1.204\times {10}^{24}$ phosphine molecules.