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A radioisotope has a half life of 10 day...

A radioisotope has a half life of 10 days. If tofay there is `125 g ` of it left, what was its mass 40 days earlier ?

A

`600g`

B

`1000g`

C

`1250g`

D

`2000g`

Text Solution

Verified by Experts

The correct Answer is:
D
`T=nxxt_(1//2)`
`:. n=(40)/(10)=4`
`N=((1)/(2))^(n)N_(0)`
`:. N_(0)=125xx(2)^(4)=125xx16=2000`
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CENGAGE CHEMISTRY-NUCLEAR CHEMISTRY-Ex6.3 Objective
  1. Radiactive decay is a reaction of

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  2. Quantity of radiactive material which undergoes 10^(6) disintegrations...

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  3. One curie of activity is equivalent to

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  4. The unit for radioactive constant is

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  5. The relation between half-life period (t(1//2)) and disintegration con...

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  6. If 2g of an isotope has a half- life of 7 days, the half life of 1g s...

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  7. Half-life of a radioactive disintegration (A rarr B) having rate const...

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  8. C^(14) has a half- life of 5760 years. 100mg of the sample containing ...

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  9. If 3//4 quantity of a radioactive substance disintegrates in 2 hours, ...

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  10. The initial mass of a radioactive element is 40g. How many grams of it...

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  11. A radioisotope has a half life of 10 days. If tofay there is 125 g of...

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  12. The half- life periods of four isotopes are give below : (i) 7.6 yea...

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  13. Ra^(226) has half life of 1600 years. The number of disintegration per...

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  14. The decay constant of Ra^(226) is 1.37xx10^(-11)s^(-1). A sample of Ra...

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  15. The number of alpha- particles emitted per second by 1g of Ra^(226) is...

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  16. Radioactivity of a radioactive element remains 1//10 of the original r...

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  17. At radioactive equilibrium, the ratio between two atoms of radioactive...

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  18. The decay constant for an alpha- decay of Th^(232) is 1.58xx10^(-10)s^...

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  19. What percentage of decay takes place in the average life of a substan...

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  20. The half life of Ra is 1600 years. The fraction of a sample of Ra that...

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