The amount of energy consumed or emitted during a nuclear reaction is known as the Q value. I can be determined from the difference between the masses of the initial reactants and the masses of the final products of a nuclear reaction. (MeV is a unit of energy).

Given that

Nuclear reaction of Uranium - 238

^{238}_{92} U + ^1_0 n \rightarrow ^{140}_{58} Ce + ^{99}_{44} Ru

m(^{238}_{92} U) = 238.05079 u

m (^{140}_{58} Ce) = 139.90543 u

m(^{99}_{44} Ru) = 98.90594 u

m(^1_0 n) = 1.00867

Step 1: Calculating the Q-value of the Nuclear reaction

Q -value = \text{ mass of } ^{238}_{92} U + \text{ mass of } ^1_0 n - \text{ mass of } ^{140}_{58} Ce - \text{ mass of } ^{99}_{44} Ru

Q-value [math] = [238.05079 + 1.00867 - 139.90543 u - 98.90594]c^2 [/math]

Q-value = 0.24809 c^2 * 931.5 MeV/c^2 u

Q-value = 231.0 MeV

Hence, Q-value of the Nuclear reaction = 231.0 MeV