Question

Number of atoms in 558.5 gram Fe (at. wt. of Fe = 55.85 g mol⁻¹)
is
(a) twice that in 60 g carbon (b) 6.023 × 10²²
(c) half that in 8 g He (d) 558.5 × 6.023 × 10²³

Answer 1

Number of atoms in 558.5 gram Fe is equal to twice that in 60 g of carbon

Explanation:

Number of moles of any substance is the ratio in between the mass to the molecular mass of that substance.

• $Number\,of\,moles=\frac{Number\,of\,atoms}{Molecular\,mass}$
• Given that number of atoms = 558.5 grams
• $\therefore Numer\,of\,moles =\frac{558.5}{55.85} =10$  
• One mole of any substance contain number of particles =$6.02\times10^{23}$  
• Atomic weight of carbon = 12
• Thus number moles of 60 g carbon = $\frac{60}{12} =5$
• $\therefore$ 10 moles of Fe has the number atoms that are equal to twice that in 60 g of carbon.
• Therefore, the correct answer is option (a)