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Question

11. You are performing an experiment that uses 113Ag. 113Ag is radioactive, decays by beta minus emission ( β), and has a half-life of 5.3 hours. It requires 31.8 hours to ship the material from the warehouse to your laboratory. How many grams should you order if the experiment requires that you have 40 grams to begin the experiment.

a. 240 g

b. 6.67 g

c. .625 g

d. 2.56 x 103g

12. The isotope 206Po has a half-life of 8.8 days. If you have 5.68 x 1025 atoms of this isotope, how long will it take for the sample to decay to 3.55 x 1024 atoms?

a. 2.20 days

b. 141 days

c. 35.2 days

d. 26.4 days

The following equations and constants may be helpful on this assignment.

c = λv E = hv E = (hc) / λ λ = h / (mv) c = 3 x 10 8m/s h = 6.626 X 10-34 Js

13. An electron with a mass of 9.11 x 10-31 kg and traveling at a velocity of 3.55 x 106 m/s has a wavelength which is measurable. What is the wavelength?

a. 2.58 x 103 m

b. 9.28 x 1031 m

c. 2.05 x 10-10 m

d. 4.65 x 10-10 m

Answer 1

11)

ln(100/50) = kx5.3 hrs

k = 0.1308 hrs^-1

ln(Ao/40g) = 0.1308 x 31.8

ln(Ao/40) = 4.159

Ao/40 = 64.04

Ao = 2561 g

ANSWER d) 2.56x10^3 grams

12)

ln(100/50) = kx8.8

k = 0.0788 day^-1

ln(5.68x10^25/3.55x10^24) = 0.0788 x t

2.77 = 0.0788 x t

t = 35.2 days

ANSWER c) 35.2 days

Answer 2

the answer to twelve is (C)

Answer 3

The answer to 13 is c.