The count rate of nuclear radiation coming from a radioactive sample containing ¹²⁸I varies with time as follows.

(a) Plot ln(R₀/R) against t.

(b) From the slope of the best straight line through the points, find the decay constant λ.

(c) Calculate the half-life t_1/2.

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.

Carbon (Z = 6) with mass number 11 decays to boron (Z = 5).

(a) Is it is β⁺-decay or a β^–-decay?

(b) The half-life of the decay scheme is 20.3 minutes. How much time will elapse before a mixture of 90% carbon-11 and 10% boron-11 (by the number of atoms) converts itself into a mixture of 10% carbon-11 and 90% boron-11?

A vessel of volume 125 cm³ contains tritium (³H, t_1/2 = 12.3 y) at 500 kPa and 300 K. Calculate the activity of the gas.

Calculate the Q-values of the following fusion reactions:

(a)

(b)

(c)

Atomic masses are = 2.014102 u, = 3.016049 u, = 3.016029 u, = 4.002603 u.