Question

Total mass of neutrons in 7 mg of ${}^{14}C$ is :

• A. $3\times {10}^{20}$ kg
• B. $4\times {10}^{-6}$ kg
• C. $5\times {10}^{-7}$ kg
• D. $4\times {10}^{-7}$ kg

Answer 1

The correct option is B $4\times {10}^{-6}$ kg

Mass of one neutron = $1.67493{10}^{-27}kg$.

Mass of total neutrons in $7g$ of $14C$ $=(2.4092\times {10}^{21})(1.67493\times {10}^{-27}kg)$

$=4.0352\times {10}^{-6}kg$