THE HALF-LIFE OF ZN-71 IS 2.4 MINUTES. IF ONE
HAD 100.0 G AT THE BEGINNING, HOW MANY GRAMS
WOULD BE LEFT AFTER 7.2 MINUTES HAS ELAPSED?
1.
2.
3.
4.
100 g
50 g
25 g
12.5 g
1
2.4
100 g
50 g
2
4.8
25 g
3
7.2
12.5 g
OS-182 HAS A HALF-LIFE OF 21.5 HOURS. HOW MANY
GRAMS OF A 10.0 GRAM SAMPLE WOULD HAVE DECAYED
AFTER EXACTLY THREE HALF-LIVES?
1.
2.
3.
4.
10 g
2.5 g
1.25 g
5g
1
10
21.5 5 g
2
43
3
64.5 1.25 g
2.5 g
AFTER 24.0 DAYS, 2.00 MILLIGRAMS OF AN ORIGINAL
128.0 MILLIGRAM SAMPLE REMAIN.
WHAT IS THE HALF-LIFE OF THE SAMPLE?
1.
2.
3.
4.
4
2
5
6
1
128 mg
64 mg
2
32 mg
3
16 mg
4
8 mg
5
4 mg
6
24.0 2 mg
FERMIUM-253 HAS A HALF-LIFE OF 0.334 SECONDS. A
RADIOACTIVE SAMPLE IS CONSIDERED TO BE COMPLETELY
DECAYED AFTER 10 HALF-LIVES. HOW MUCH TIME WILL ELAPSE
FOR THIS SAMPLE TO BE CONSIDERED GONE?
1.
2.
3.
4.
1 second
2 seconds
3 seconds
3.34 seconds
1
.334
2
.668
3
1.002
4
1.336
5
1.67
6
2.004
7
2.338
8
2.672
9
3.006
10
3.34 seconds
100.0 GRAMS OF AN ISOTOPE WITH HALF-LIFE OF 26
HOURS IS PRESENT AT TIME ZERO. HOW MUCH TIME
WILL ELAPSE BEFORE 50 GRAMS REMAINS?
1.
2.
3.
4.
100 g
50 g
26 g
0g
1
26 hrs
100
50 g
RN-222 HAS A HALF-LIFE OF 3.82 DAYS. HOW LONG
BEFORE ONLY 1/16 OF THE ORIGINAL SAMPLE REMAINS?
1.
2.
3.
4
15.28 days
11.46 day
7.64 days
3.82 days
1
3.82
Original
sample
1/2
2
7.64
1/4
3
11.46
1/8
4
15.28
1/16