The Q value of a nuclear reaction `A + b to C + d` is defined by `Q = [m_A + m_b - m_C - m_d]c^2`, where the masses refer to the respective nuclei. Determine from the given data the Q-value of the following reactions and state whether the reactions are exothermic or endothermic.
`i. ""_1^1H + ""1^3H to ""1^2H + ""1^2H`
`ii. ""_6^12C + ""6^12C to ""10^20Ne + ""_2^4He`
Atomic masses are given to be
`m(""_1^2H) = 2.014102u`
`m(""_1^3H) = 3.016049 u`
`m(""_6^12C) = 12.000000u`
`m_(""_10^20Ne) = 19.992439 u`.

Explanation

`i. ""_1^1H + ""_1^3H to ""1^2H + ""_1^2H`
`Q = [{m(""1^2H) + m(""_1^3H)}-{m(""_1^2H) + m(""_1^2H)}]c^2`
`=(4.02387 - 4.028204)931`
`= -4.033 MeV` (Negative sign shows that the reaction is endothermic)
ii. `Q = [2m(""_6^12C) - {m(""10^(20)Ne) + m(""_2^4He)}]c^2`
`={2 xx 12 -(19.992439 + 4.002603)}931`
`=4.618 MeV` (exothermic reaction)