Question

radioactive isotope|half - life
rubidium - 91|58.4 seconds
iodine - 131|8 days
cobalt - 60|5 years
carbon - 14|5730 years
cesium - 135|2.3 x 10^6 years
uranium - 238|4.5 x 10^9 years
which radioactive isotope would take the least amount of time to become stable?
○ rubidium - 91
○ iodine - 131
○ cesium - 135
○ uranium - 238

Explanation:

Step1: Compare half - life values

Compare the given half - life values of different radioactive isotopes. Rubidium - 91 has a half - life of 58.4 seconds, Iodine - 131 has 8 days, Cobalt - 60 has 5 years, Carbon - 14 has 5730 years, Cesium - 135 has $2.3\times10^{6}$ years and Uranium - 238 has $4.5\times10^{9}$ years.

Step2: Identify the shortest half - life

The shortest half - life among them is 58.4 seconds which belongs to Rubidium - 91. A shorter half - life means the isotope will decay and become stable in a shorter time.

Answer:

rubidium-91