Iodine-131 is a radioactive isotope. after 7.00 days, 54.7% of a sample of 131i remains. what is the half-life of 131i?

The half-life of ¹³¹I is 8.04 days.

Explanation:

We can calculate the half-life of 131I using the formula:

Where 0.547 is the percentage of the sample that remains, 7.00 is the amount of days that have passed, and α is the half-life.

We use Log on both sides of the equation:

And solve for α:

α = 8.04 days

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.