Question

One atom of an element weighs $3.32\times {10}^{-23}$ g. How many number of gram atoms are there in 20 kg of the element?

• A. 2000
• B. 20
• C. 200
• D. 1000

Answer 1

The correct option is D 1000

Mass of one atom $=3.32\times {10}^{-23}$g

Mass of $n$ atoms = $20kg=20000g$

$\therefore ,n=\frac{20000}{3.32\times {10}^{-23}}=6.024\times {10}^{26}$ atoms

1 gram atom $=6.023\times {10}^{23}$ atoms

Number of gram atoms $\times 6.023\times {10}^{23}=6.024\times {10}^{26}$

Number of gram atoms $=1000$

So, the correct option is $D$