\[8gm\] of the radioactive isotope, cesium-137 were collected on February 1 and kept in a sealed tube. On July 1, it was found that only \[0.25gm\] of it remained. So the half-life period of the isotope is [KCET 1989]

\[8gm\] of the radioactive isotope, cesium-137 were collected on Febru

1.	\[8gm\] of the radioactive isotope, cesium-137 were collected on February 1 and kept in a sealed tube. On July 1, it was found that only \[0.25gm\] of it remained. So the half-life period of the isotope is [KCET 1989]
A.	37.5 days
B.	30 days
C.	25 days
D.	50 days
Answer» C. 25 days

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\[8gm\] of the radioactive isotope, cesium-137 were collected on February 1 and kept in a sealed tube. On July 1, it was found that only \[0.25gm\] of it remained. So the half-life period of the isotope is [KCET 1989]

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