Thorium-234 has a half life of about 25 days. What percent of the thorium will remain after 125 days

3.125% will remain after 125 days

Explanation:

Given dа ta:

Half life of Th-234 = 25 days

Percent of thorium remain after 125 days = ?

Solution:

Number of half lives = T elapsed / half life

Number of half lives = 125 days / 25 days

Number of half lives = 5

At time zero = 100%

At 1st half life = 100%/2 = 50%

At second half life = 50%/2 = 25%

At third half life = 25% / 2 = 12.5%

At 4th half life = 12.5% / 2 = 6.25%

At 5th half life = 6.25% / 2 = 3.125%