What percentage of original radioactive atoms is left after four half-lives?
After the fourth half-life, it will reduce to half and the remaining concentration. After the fifth half-life, it will reduce to half of the remaining concentration. Therefore, from the above explanation the correct option is (C)3.125%.
What percent of a parent isotope would remain after two half-lives?
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.
| 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 much of the parent isotope is left after 4 half lives?
62.5 g
What percentage of parent atoms will be present after 5 half lives?
Half-Lives
| No. of half lives passed |
Percent parent remaining |
Percent daughter produced |
| 5 |
3.125 |
96.875 |
| 6 |
1.563 |
98.437 |
| 7 |
0.781 |
99.219 |
| 8 |
0.391 |
99.609 |
Which parent isotope has the slowest rate of radioactive decay?
It is a rare chemical element found in the Earth’s crust with an average of 3 grams per tonne. The uranium image has suffered from its association with the first atomic bombs. Its reputation as a malevolent radioisotope, however, is undeserved: in fact, the decay rate of uranium is among the slowest known to man.
What percentage of a sample’s original radioactivity remains after five half-lives?
After 3 half-lives there will be 12.5% of the original isotope, and 87.5% of the decay product. After 4 half-lives there will be 6.25% of the original isotope, and 93.75% of the decay product. After 5 half-lives there will be 3.125% of the original isotope, and 96.875% of the decay product.
How much of a material remains after 5 half lives?
Hence, after 5 half lives the quantity that would remain would be: 321 which is 3. 125% Was this answer helpful?
What percentage of a sample remains after four half lives?
For example the amount of a sample remaining after four half-lives could be expressed as: a fraction – a ½ of a ½ of a ½ of a ½ remains, which is ½ × ½ × ½ × ½ = 1/16 of the original sample. a decimal – 1/16 = 0.0625 of the original sample.
How long is a radioactive half-life?
Half-life, in radioactivity, the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or, equivalently, the time interval required for the number of disintegrations per second of a radioactive …
Does a shorter half-life mean more radioactive?
In general there is an inverse relation between the half-life and the intensity of radioactivity of an isotope. Isotopes with a long half-life decay very slowly, and so produce fewer radioactive decays per second; their intensity is less. Istopes with shorter half-lives are more intense.
What happens to a radioactive sample after one half-life?
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. Half of what remains decay in the next half-life, and half of those in the next, and so on.
What Causes Half-Life?
As a radioisotope atom decays to a more stable atom, it emits radiation only once. The decay of radioactive elements occurs at a fixed rate. The half-life of a radioisotope is the time required for one half of the amount of unstable material to degrade into a more stable material.
Is lifetime the same as Half Life?
Note that the radioactive half-life is not the same as the average lifetime, the half-life being 0.693 times the average lifetime. The example that causes the most confusion is the decay of the free neutron with a half-life of 10.3 minutes and an average lifetime of 14.9 minutes.
Is a short half life good?
a short half-life usually means more withdrawal problems. a long half-life usually means fewer withdrawal problems.
Is long half life more dangerous?
A short half-life is more dangerous. A long half-life stays dangerous longer. Well, but there are exceptions. To make a really reasonable assessment of the risk posed by radioactive material, you have to know not only the half-life but the decay products, which may also be radioactive or could be toxic.
Why is Half Life important in nuclear waste?
In a nutshell, the radiological half-life is important in radiation control because long-lived radionuclides, once released, are around for longer time periods than are shorter-lived species. Long-lived radionuclides released to the environment will be present for longer times than short-lived nuclides.
Why is half-life of a drug important?
Understanding the concept of half-life is useful for determining excretion rates as well as steady-state concentrations for any specific drug. Different drugs have different half-lives; however, they all follow this rule: after one half-life has passed, 50% of the initial drug amount is removed from the body.