Question

There is a 30 g sample of Be-11. It has a half-life of about 14 seconds.
How much will be left after 28 seconds?
A. 3.75 g
B. 7.5 g
C. 15 g
D. 30 g

Answer 1

Answer:

7.5 g

Explanation:

As life-time last 14 seconds,

1 life-time = half of the initial amount = 30/2 = 15 g

2 second life-time = 28 seconds =  15 g /2 = 7.5 g

Answer 2

Answer:

Answer:

7.5 g

Explanation:

As life-time last 14 seconds,

1 life-time = half of the initial amount = 30/2 = 15 g

2 second life-time = 28 seconds =  15 g /2 = 7.5 g