Table of Contents

## How much of a sample remains after 3 half-lives?

Answer and Explanation: After three half-lives 1/8 (12.5%) of the original sample remains. A half-life is the amount of time it takes for one-half of a sample to undergo…

## What mass of radioactive isotope will be left after 3 half-lives?

after three half lives or 3.9 years, 11.25 mg will be left.

**What percentage of a radioactive isotope would remain after three half-lives quizlet?**

After one half life, 50% of the radioactive element remains undecayed. After two half-lives, 25% remains undecayed. After three half-lives, 12.5% remains undecayed. After four half-lives, 6.25% remains undecayed.

**What percentage of daughter isotopes are left after 3 half-lives?**

Pretend you find a rock with 3.125% parent atoms and 96.875% daughter atoms. How many half lives have passed?…Half-Lives.

No. of half lives passed | Percent parent remaining | Percent daughter produced |
---|---|---|

1 | 50 | 50 |

2 | 25 | 75 |

3 | 12.5 | 87.5 |

4 | 6.25 | 93.75 |

### What fraction of a radioactive isotope remains unchanged after 2 half-lives?

Explanation: After 1 half life , clearly HALF of the original isotope remains. And after TWO half-lives, a HALF + HALF of a HALF , i.e. 34 of the original mass has decayed.

### How do you calculate age from a half-life?

To determine the absolute age of this mineral sample, we simply multiply y (=0.518) times the half life of the parent atom (=2.7 million years). Thus, the absolute age of sample = y * half-life = 0.518 * 2.7 million years = 1.40 million years.

**What percentage of parent isotope remains after three half-lives of radioactive decay have elapsed?**

Answer and Explanation: Only 12.5 percent of the original sample of a radioactive parent isotope will remain after three half-lives have passed.

**What percent of potassium-40 will remain after 3 half-lives?**

After another 1300 million years ( three half lives or 3900 million years) 50 /2 = 25 g decays and 25 g remains left.

#### How many half-lives have passed?

10.3: Half-Life

Number of Half-Lives Passed | Fraction Remaining | Percentage Remaining |
---|---|---|

1 | 1/2 | 50 |

2 | 1/4 | 25 |

3 | 1/8 | 12.5 |

4 | 1/16 | 6.25 |

#### What does the half life of a radioisotope correspond to?

The nucleus of a given radioisotope decays at a constant rate that is unaffected by temperature, pressure, or other conditions outside the nucleus. This rate of decay is called the half-life. The half-life is the length of time it takes for half of the original amount of the radioisotope to decay to another element.

**How to calculate half life of radioactive isotope?**

Enter the initial and remaining quantity of the element in the corresponding input boxes.

**Which radioactive isotopes has the shortest half life?**

You may wonder which naturally-occurring element has the shortest half-life. That would be francium, element 87, whose longest-lived isotope, francium-223, has a half-life of 22 minutes, decaying either into radium by beta decay or astatine by alpha emission. It was discovered in nature in 1939 (the last radioactive element to be found in nature rather than by synthesis) and is present in trace amounts in uranium and thorium ores.

## Which isotope has a relatively short half-life?

Polonium-214 has a relatively short half life of 164 s. How many seconds would it take for 8.0 g of this isotope to decay to 0.25 g? Answer Verified 70.8k + views Hint: In a radioactive decay, the half life is defined as the period of time after which there is a 50% chance that an atom will have undergone nuclear decay.