Question

The table shows the decay in a 59 g sample of bismuth 212 overtime.

if bismuth 212 has a half-life of 60.5 seconds, how many grams of the sample will be left after 121 seconds?

A. 3.69 g
B. 7.38 g
C. 14.75 g
D. 29.5 g

Answer 1

Answer: C

14.75g

Explanation:

Given that the half life time = 60.5s

Let No = initial mass = 59g

N = decayed mass

At time t = 0, No = 59g

At time t = 60.5s,

N = No/2 = 59/2

= 29.5g

At time t = 121

N = 29.5/2 = 14.75g

Therefore N = 14.75g