Question

juliet started working with a radioactive substance. in 1997, she started with 200 g. when she measured again in 2002, she had 100 g left. in 2007, she had 50 g. which substance is she most likely measuring? 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

Explanation:

Step1: Calculate time intervals

From 1997 - 2002 is 5 years, from 2002 - 2007 is 5 years.

Step2: Analyze half - life

The amount of the substance halves every 5 years, so the half - life of the substance is 5 years.

Answer:

cobalt - 60