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sattari [20]
4 years ago
10

3.

Chemistry
1 answer:
sp2606 [1]4 years ago
8 0
<h3>Answer:</h3>

20 g

<h3>Explanation:</h3>

We are given;

Original mass of K-40 before decay = 80 g

Half life of Potassium-40 = 1.25 billion years

Time taken by the decay = 2.5 billion years

We are required to calculate the mass of K-10 that will remain after 2.5 billion years.

Using the formula;

Remaining mass = Original mass × (1/2)^n

where n is the number of half lives

Number of half lives, n = Time taken ÷ half-life

                                     = 2.5 billion years ÷ 1.25 billion years

                                     = 2

Remaining mass = 80 g × (0.5)^2

                            = 80 g × 0.25      

                            = 20 g

Therefore, the mass of K-40 isotope that will remain after 2.5 billion years is 20 g.

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