Disintegration rate of a sample is 10^10 per
hour at 20 hrs from the start. It reduces
to 6.3 × 109
per hour after 30 hours.
Calculate its half life and the initial
number of radioactive atoms in the
sample
Answers
Answer:
Explanation:ANSWER
Two radioactive nuclei X and Y initially contain equal number of atoms. The half life is 1 hour and 2 hours respectively.
Calculate the radio of their rates of disintegration after two hours.
Given, nucleii X and Y contain equal number of atoms.
Half-life of X, T
1
=1hr
Half-life of Y, T
2
=2hr
Radio of radioactive sample of X left after 2 hours,
N
1
=(
2
1
)
2/1
N
0
=
4
1
N
0
Radio of radioactive sample of Y left after 2 hours,
N
2
=(
2
1
)
2/2
N
0
=
2
1
N
0
Now, decay rate is given by,
R=λN=
T
1/2
0.693N
⇒R∝
T
1/2
N
R
2
R
1
=
(T
1/2
)
1
(T
1/2
)
2
×
N
2
N
1
i.e., =
1
2
×
2
N
0
4
N
0
=1