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.

²²⁸Th emits an alpha particle to reduce to ²²⁴Ra. Calculate the kinetic energy of the alpha particle emitted in the following decay:

²²⁸Th → ²²⁴Ra* + α

²²⁴Ra* → ²²⁴Ra + γ (217 keV).

Atomic mass of ²²⁸Th is 228.028726u, that of ²²⁴Ra is 224.020196 u and that of is 4.00260 u.

Calculate the maximum kinetic energy of the beta particle emitted in the following decay scheme:

¹²N → ¹²C* + e⁺ + v

¹²C* → ¹²C + γ (4.43 MeV).

The atomic mass of ¹²N is 12.018613 u.