50% of the nuclei in a radioactive sample decay in one half life. What percent decay...

Question

Question

50% of the nuclei in a radioactive sample decay in one half life. What percent decay in four half lives?

Answer 1

Answer #1

N = No*(1/2)^(t/T_1/2)

t = 4T_1/2

=> N = No*(1/2)^(4) = No/16 this is the remaining after 4 half lives.

=> % decay = 100*(1 - 1/16) = 93.75 %

Answer 2

Similar Homework Help Questions

A radioactive sample contains two different types of radioactive nuclei: A, with half-life 9.0 days, and...

A radioactive sample contains two different types of radioactive nuclei: A, with half-life 9.0 days, and B, with half-life 18.0 days. Initially, the decay rate of the A-type nucleus is 256 times that of the B-type nucleus. 1) When will their decay rates be equal?
Radioactive Decay - Half-life and Activity 1 Radioactive decay - Half-life Time 0 1000 21 31...

Radioactive Decay - Half-life and Activity 1 Radioactive decay - Half-life Time 0 1000 21 31 750 N 1.000.000 500,000 250,000 125,000 62,500 31.250 15.625 7813 3.506 1.953 977 51 6 500 7 BI . 101 250 125 0 tie 21.234.41516171819, 1012 Time in multiples of A radioactive sample's half-life is 30.2 years. 1 year = 365 days, 1 day = 24 hours, 1 hour - 60 minutes, 1 minute = 60 seconds (a) Find its decay constant in year...
A sample contains 7.10×104 radioactive nuclei. In a time of 3 minutes, 3.50×103 of the nuclei...

A sample contains 7.10×104 radioactive nuclei. In a time of 3 minutes, 3.50×103 of the nuclei decay. Evaluate the half life of the sample (in minutes).

a radioactive sample has a half life of 10s if 20,000 nuclei are present at t=10s...

a radioactive sample has a half life of 10s if 20,000 nuclei are present at t=10s how many nuclei will be there at t = 40 s
An unknown radioactive element decays into non-radioactive substances. In 760 days the radioactivity of a sample decreases by 77 percent. (a) What is the half-life of the element? half-life: (days) (b) How long will it take for a sample of 1

An unknown radioactive element decays into non-radioactive substances. In 760 days the radioactivity of a sample decreases by 77 percent.(a) What is the half-life of the element?half-life: (days)(b) How long will it take for a sample of 100 mg to decay to 68 mg?time needed: (days)
PS2.7 The half-life for the (first-order) radioactive decay of 14C is 5730 years. An archaeological sample...

PS2.7 The half-life for the (first-order) radioactive decay of 14C is 5730 years. An archaeological sample contained wood that had only 69 percent of the 14C found in living trees. What is its age?

The half-life for the radioactive decay of calcium-47 is 4.5 d. if a sample has an...

The half-life for the radioactive decay of calcium-47 is 4.5 d. if a sample has an activity of 4.5 Ci after 9.0 d, what was the initial activity of the sample?
91. If the half – life of a sample of radioactive material is 60 days, what...

91. If the half – life of a sample of radioactive material is 60 days, what fraction of the original radioactive nuclei will remain after 120 days.
(b) [5 marks] Using first principles, derive the radioactive decay rate for nuclei whose decay constant...

(b) [5 marks] Using first principles, derive the radioactive decay rate for nuclei whose decay constant is ?. Here R,-??, is the rate of decay at t-0 [5 marks] A count-rate meter is used to measure the activity of a given sample. At one instance it shows 4750 counts per minute (cpm). Five minutes later it shows 2700 cpm. Find the decay constant and the half-life of the sample. (c) (d) [5 Marks] For alpha decay, show that 13 markel...

What's this nuclide's half-life? A radioactive sample containing 1.20×1017 nuclei has activity 2.45×1012 Bq .

What's this nuclide's half-life? A radioactive sample containing 1.20×1017 nuclei has activity 2.45×1012 Bq .