Advertisements
Advertisements
प्रश्न
A radioactive substance decays to (1/10)th of its original value in 56 days. Calculate its decay constant.
Advertisements
उत्तर
Here, `("N"("t"))/"N" = 1/10` and t = 56 days
We have, `("N"("t"))/"N"_0 = "e"^{-lambda"t"}`
∴ `1/10 = "e"^{-lambda"t"}`
∴ `"e"^{lambda"t"} = 10`
∴ `lambda"t" = log_"e"10`
∴ `lambda = (log_"e"10)/"t"`
= `(2.303 xx log 10)/56`
= `2.303/56`
= antilog {log(2.303) − log (56)}
= antilog {0.3623 − 1.7481}
= antilog {`overline2` .6142}
= 4.113 × 10−2 per day
The decay constant is 4.113 × 10−2 per day.
संबंधित प्रश्न
What is gamma decay?
Sample of carbon obtained from any living organism has a decay rate of 15.3 decays per gram per minute. A sample of carbon obtained from very old charcoal shows a disintegration rate of 12.3 disintegrations per gram per minute. Determine the age of the old sample given the decay constant of carbon to be 3.839 × 10−12per second.
Describe alpha, beta and gamma decays and write down the formulae for the energies generated in each of these decays.
Complete the following equation describing nuclear decay.
\[\ce{_88^226Ra->_2^4\alpha {+}}\] ______.
Complete the following equation describing nuclear decay.
\[\ce{_8^19O->e^- { +}}\] _____
Complete the following equation describing nuclear decay.
\[\ce{_90^228Th->\alpha { +}}\] _____
The half-life of 18F is 110 minutes. What fraction of 18F sample decays in 20 minutes?
A 3/4 of the original amount of radioisotope decays in 60 minutes. What is its half-life?
A sample of old wood shows 7.0 dps/g. If the fresh sample of tree shows 16.0 dps/g, how old is the given sample of wood? (Half-life of 14C is 5730 y)
Show that half life period of radioactive material varies inversely to decay constant λ.
Show that for radioactive decay N(t) = `"N"_"O" "e"^{-λ"t"}`, where symbols have their usual meaning.
Obtain an expression for the half-lifetime of radioactive material. Hence state the relation between an average life and half life time of radioactive material.
A radioactive substance of half-life 69.3 days is kept in a container. The time in which 80% of the substance will disintegrate will be ______
[take ln(5) = 1.61]
Most excited states of an atom have life times of about ____________.
The activity of a radioactive sample ____________.
What is alpha decay?
What is beta decay?
The radioactivity of a sample is R1 at a time T1 and R2 at a time T2. If the half-life of the specimen is T, the number of atoms that have disintegrated in the time (T1 - T2) is proportional to ______.
A radioactive sample S1 having the activity A1 has twice the number of nuclei as another sample S2 of activity A2 If A2 = 2A1 then the ratio of half-life of S1 to the half-life of S2 is ______.
The half-life of a radioactive substance is 10 days. The time taken for the `(7/8)^"th"` of the sample of disintegrates is ______.
The graph obtained by plotting loge (A) [A is the activity of a radioactive sample] against t (time) out of the following is:
If the number of nuclei of a radioactive substance becomes `1/e` times the initial number in 10 days, what is the decay constant of the substance?
The half-life of \[\ce{^238_92U}\] undergoing ∝- -decay is 4.5 × 109 years. What is the activity of 1g sample of \[\ce{^238_92U}\]?
Define half-life period.
