The half- life of radioactive cobalt- 60 is 5.26 years.  a) Calculate the mean life and the disintegration constant.  b) What is the activity of a 1- gm sample of Co - 60? Express this activity in curies and  in rutherfords.

Please help me answer the following.

1) If the activity of a purely radioactive sample of 55Fe is measured to be 0.5 mCi. What is the number of nuclei of this isotope present after 5.4 years. 2) 226Ra (t₁/2 = 1600 y) alpha decays to the 1st excited state of nucleus X with branching ratio 6% and alpha decays to the ground state of X with branching ratio 94%. Calculate the partial half-life for the first mode transition (the one to the first excited state of X). 3) Fill the missing and decide the type of decay in the following decays: a) Co* → [ ] + Co b) ¹50 [ ] + [ ] + ¹5N 40 c) 10K + [ ] 18Ar d) 21 Po 84 e) ¹3 Be →>> 2a + [ ] ¹2Be + [ ]

3. (a) Calculate the decay constant for cobalt-60 (T1/2 = 5.26 Years) in units of week-¹ (b) Calculate the activity of a 5000-Ci cobalt-60 source after 10 years.