Question

${}^{14}C$ has a half life of $5760$ years. $100$ $mg$ of the sample containing ${}^{14}C$ is reduced to $25$ $mg$ is:

• A. $11520$ years
• B. $2880$ years
• C. $1440$ years
• D. $17280$ years

Answer 1

The correct option is A $11520$ years

Initial sample =$100mg$

Final Sample=$25mg$

Sample becomes one-fourth after two half lives i.e $5760\times 2=11520years$.