Table of Contents

- 1 How do you find the percentage of radioactive atoms that are left after each half-life?
- 2 How many of the decaying atoms of decaying isotope remain unchanged after three half lives?
- 3 What is N in radioactive decay?
- 4 What is the rate of radioactive decay?
- 5 What percentage of a radioactive element will be left after?
- 6 How much of the radioactive isotope remains?
- 7 What is rate of disintegration?

## How do you find the percentage of radioactive atoms that are left after each half-life?

Thus the half-life of a nuclear decay process is the time required for the number of unstable nuclei to decrease from [A]0 to 1/2[A]0….Radioactive Decay Rates.

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\% |

## How many of the decaying atoms of decaying isotope remain unchanged after three half lives?

Explanation: Three half lives corresponds to (12)3 . So a 18 quantity of the original isotope is retained.

**How many half lives are required before a quantity of radioactive material has decayed to less than 1\% of its original value?**

Radioactive decay reduces the number of radioactive nuclei over time. In one half-life t1/2, the number decreases to half of its original value.

### What is N in radioactive decay?

Suppose N is the size of a population of radioactive atoms at a given time t, and dN is the amount by which the population decreases in time dt; then the rate of change is given by the equation dN/dt = −λN, where λ is the decay constant. …

### What is the rate of radioactive decay?

The rate of decay, or activity, of a sample of a radioactive substance is the decrease in the number of radioactive nuclei per unit time.

**What percentage of radioactive substance is left after 4 half-lives?**

Half-live is the time after which the final amount is half of the initial amount of radioactive substance. Therefore, the amount of undecayed radioactive substance is 6.25\% of the original amount. The correct answer is option A.

#### What percentage of a radioactive element will be left after?

Therefore, after one half-life, 50 percent of the initial parent nuclei remain; after two half-lives, 25 percent; and so forth. The intensity of radiation from a radioactive source is related to the half-life and to the original number of radioactive atoms present.

#### How much of the radioactive isotope remains?

After 1 half-life there will be 50\% of the original isotope, and 50\% of the decay product. After 2 half-lives there will be 25\% of the original isotope, and 75\% of the decay product. After 3 half-lives there will be 12.5\% of the original isotope, and 87.5\% of the decay product.

**How do you calculate half lives?**

The time taken for half of the original population of radioactive atoms to decay is called the half-life. This relationship between half-life, the time period, t1/2, and the decay constant λ is given by t12=0.693λ t 1 2 = 0.693 λ .

## What is rate of disintegration?

Chemical Kinetics of Class 12 The rate of disintegration of a given substance depends upon the nature of disintegrating substance and its total amount. It is defined as “time during which half the amount of a given sample of the radioactive substance disintegrates”.