The mass of cesium left afer 120 years if the original mass of cesium is 8640 with an half-life of 30 years, is 540 grams.
This can be defined as the time taken for half the amount of a radioactive substance to decay.
To calculate the amount of cesium left after 120 years, we use the formua below.
Formula:
Where:
From the question,
Given:
Substitute these values into equation 1
Hence, The mass of cesium left afer 120 years is 540 grams.
Learn more about half-life here: https://brainly.com/question/25750315