The masses of ¹¹C and ¹¹B are respectively 11.0114 u and 11.0093 u. Find the maximum energy a positron can have in the β+-decay of ¹¹C to ¹¹B

Potassium -40 can decay in three modes. It can decay by β^–-emission, β⁺-emission or electron capture.

(a) Write the equations showing the end products.

(b) Find the Q-value in each of the three cases. Atomic masses of are 39.9624 u, 39.9640 u and 39.9626 u respectively.

Lithium (Z = 3) has two stable isotopes ⁶Li and ⁷Li. When neutrons are bombarded on lithium sample, electrons and α-particles are ejected. Write down the nuclear processes taking place.

Radioactive ¹³¹I has a half-life of 8.0 days. A sample containing ¹³¹I has activity 20 μ Ci at t = 0.

(a) What is its activity at t = 4.0 days?

(b) What is its decay constant at t = 4.0 days?

The half-life of a radioisotope is 10 h. Find the total number of disintegrations in the tenth hour measured from a time when the activity was 1 Ci.