Question

One atom of an element X weighs $6.644\times {10}^{-23}$. Calculate the number of gram atoms in 40 kg of it.

• A. ${10}^2$
• B. ${10}^3$
  
• C. ${10}^{-2}$
  
• D. ${10}^4$
  

Answer 1

The correct option is B ${10}^3$

The mass of $6.02\times {10}^{23}$ number of atoms = $6.644\times \times {10}^{-23}\times 6.02\times {10}^{23}$ = 40 gm /mol (gram atomic mass )

Now the number of gram atoms or moles = $\frac{mass\left(ingm\right)}{atomicmass}$ = $\frac{40\times {10}^3}{40}$ = ${10}^3$