Answer:
The correct answer is -
A. 2.6 × 10^9 years.
B. two half-lives.
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.
