If $2.0 \ g$ of a radioactive substance has a half-life of $7 \ days$,what is the half-life of a $1 \ g$ sample?

$A$ radioactive substance takes $20 \, \text{min}$ to decay $25 \%$. How many minutes will it take to decay $75 \%$?

The $C^{14}$ to $C^{12}$ ratio in a wooden article is $13\%$ that of the fresh wood. Calculate the age of the wooden article. Given that the half-life of $C^{14}$ is $5770 \ years$.

$A$ radioactive sample has a half-life of $1500 \ years$. $A$ sealed tube containing $1 \ g$ of the sample will contain after $3000 \ years$:

The half-life for radioactive decay of $^{14}C$ is $5730 \ years$. An archaeological artifact containing wood had only $80\%$ of the $^{14}C$ found in a living tree. The age of the sample is ....... $years$.

What is the order of radioactive decay of a substance?