Question

10 A. How many years would pass if only 25% of the Potassium-40 radioactive elements are left?

10B. How many half-lives has the sample gone through if only 25% of the Potassium-40 radioactive elements are left?

Answer 1

The correct answer is -

A. 2.6 × 10^9 years.

B. two half-lives.

Step-by-step explanation:

According to the question, the half-life of potassium-40 is, 1.3 × 10^9 years, which means it takes 1.3 billion years to decay or disintegrate half of the initial amount of the potassium.

The half-life of K-40 = 1.3 × 10^9

The number of half-life, => (1/2)^2 = 1/4 (25% =1/4)

n = 2

number of half life = two

the time it takes = n*half lifetime

= 2 *1.3 × 10^9

=2.6 × 10^9 years.