Question

Solve this fast

Q. A sample of radioactive substance shows an activity of 3.4 millicurie and after 600 seconds the activity shown is 1.7 millicurie. What is the half-life of radioactive sample

Answer 1

Answer:

r

1

=2.3×10

−3

curie

r

2

=1.62×10

−3

curie, when t = 600 s

∴

r

2

r

1

=

1.62×10

−3

2.3×10

−3

=

N

2

N

1

(∴r∝ Number of atoms)

K=

t

2.303

log

N

2

N

1

=

600

2.303

log

1.62

2.3

=5.84×10

−1

s

−1

∴t

1/2

=

K

0.693

=

5.84×10

−4

0.693

=1186.15s

T(average life) =

K

1

=

5.84×10

−4

1

= 1712.33 s

or,

T=1.44×t

1/2

=1.44×1186.15

= 1712.33 s