## Is 50% of a radioactive element remains after 4000 years what is the half-life?

Simply understanding that 50% is mathematically equal to half, and the definition of half life, which is the time it takes to decrease to half the original amount, will immediately lead to the answer of 4000 years.

## What is the amount of time for 50% of a sample of carbon 14 to have decayed?

5,730 years

1. 5,730 years; The graph shows that 50 percent of the carbon-14 atoms have decayed after 5,730 years, so 5,730 is the half-life of carbon-14.

**How do you find the half-life of a radioactive element?**

The time required for half of the original population of radioactive atoms to decay is called the half-life. The relationship between the half-life, T1/2, and the decay constant is given by T1/2 = 0.693/λ.

**What is half life of a element?**

The half-life of a radioactive element is the time needed for half of the material to decay. The blue and orange points represent the original number of radioactive nuclei and those that decay; the number of blue points decreases by half at each step in time.

### How do you calculate percent half-life?

As you can see from this table, the amount of reactant left after n half-lives of a first-order reaction is (1/2)n times the initial concentration….Half-Lives and Radioactive Decay Kinetics.

Number of Half-Lives | Percentage of Reactant Remaining | |
---|---|---|

1 | 100%2=50% | 12(100%)=50% |

2 | 50%2=25% | 12(12)(100%)=25% |

3 | 25%2=12.5% | 12(12)(12)(100%)=12.5% |

n | 100%2n | (12)n(100%)=(12)n% |

### How do you calculate half-life from activity?

We can calculate the mass released using Avogadro’s number and the concept of a mole if we can first find the number of nuclei N released. Since the activity R is given, and the half-life of 137Cs is found in Appendix B to be 30.2 y, we can use the equation N=0.693Nt1/2 to find N. N=Rt1/20.693.