Question

Calculate the difference in the number of carbon atoms in 1.0 g of $C-14$ isotope and 1.0 g of $C-12$ isotope.

• A. $7.2\times {10}^{21}$
• B. $6.2\times {10}^{20}$
• C. $6.2\times {10}^{22}$
• D. $7.2\times {10}^{20}$

Answer 1

The correct option is A $7.2\times {10}^{21}$

1 gram carbon $C-12$ isotope contain $1/12\times 6.023\times {10}^{23}$ atoms

1 gram carbon $C-14$ isotope contain $1/14\times 6.023\times {10}^{23}$ atoms

difference of atoms in $C-12$ and $C-14$ $=6.023\times {10}^{23}(1/12-1/14)$

$=0.011\times 6.023\times {10}^{23}$

$=7.17\times {10}^{21}$ or $7.2\times {10}^{21}$