Question

Radioactive Decay - Half-life and Activity 1 Radioactive decay - Half-life Time 0 1000 21 31 750 N 1.000.000 500,000 250,000 125,000 62,500 31.250 15.625 7813 3.506 1.953 977 51 6 500 7 BI . 101 250 125 0 tie 21.234.41516171819, 1012 Time in multiples of A radioactive sample's half-life is 30.2 years. 1 year = 365 days, 1 day = 24 hours, 1 hour - 60 minutes, 1 minute = 60 seconds (a) Find its decay constant in year 1. Keep 4 decimal places. Enter a number yr-1 Submit (5 attempts remaining) Find its decay constant in s 1. Write the result in terms of 10-10 5-1. Keep 4 decimal places. Enter a number *10-19-1 Submit (5 attempts remaining) Case 1: The initial sample is 5.50 kg. (b) What is the mass (in kg) of the radioactive material that remains in the sample after 9.0 yr? Keep 3 decimal places. Enter a number kg Submit (5 attempts remaining) What is the mass (in kg) of the radioactive material that has decayed in 9.0 yr (from the initial sample)? Keep 3 decimal places. Enter a number kg Submit (5 attempts remaining) Case 2: The initial sample contains 9.60x10^10 radioactive nuclei. (c) What is the number of the radioactive nuclei that remain in the sample after 9.0 yr (since the initial time)? Write the result in terms of 1010. Keep 3 decimal places. Enter a number X1010 Submit (5 attempts remaining) (d) What is the initial activity in decays/s (Bq)? Keep 2 decimal places. Enter a number decays/s (Bq) Submit (5 attempts remaining) What is the activity in decays/s (Bq) after 9.0 yr (since the initial time)? Keep 2 decimal places. Enter a number decays/s (B) Submit (5 attempts remaining)

Answer 1

Q1. al Given half life constant 1 = In 2 tye 04693 30.2 t1/2 = 30.2 30. 2 years decay 12 0.0229 year! (6) Now to fud in second in neue year = 365 x 24 x 60 x 60 sec. - 3.154. xidsen ܘܘ 7-275x10-10 See 1 0.0229 3.154 X 167 (C) N= No e it Whene N: een Ne ; miliale To N at t- remaining quantily quanlity 0.022949 N = No e Na No No 0.2061 1.2289 e 0.20 if initial mass 5,5 Kg es Now 4.4755 Km → Mr. @ Mass decayed wal 5.5. mais = sos 1.2289 Mo - MR 5.5-4.4755 1.0245 kg Md. 10245 Kg 1 Case: 2 No = 9.6.xlolo Na No @ 9:6.81010 1.2289 2 1.812x160 20-2261 @ Activity Nai ( = 7:275X10-10 Seel Initial Vakcox 7.215 X1010 aycars AzN^= 7.812 X 1.215 356-83decayols 69.84 decayels at t-