Q12 / 97 · NTA Abhyas (JEE Main) 2020 · Physics · Nuclear Physics

Li7 fuses with a proton according to the nuclear reaction given below:

p + 7Li → 4He + 4He

Given that the atomic masses of 1H, 4He and 7Li are 1.007825 u, 4.002603 u and 7.016004 u respectively, where u=931.5 MeV/c2, then the Q-value of the reaction is

  • Correct answer
    A
    17.35 MeV
  • B

    18.06 MeV

  • C

    177.35 MeV

  • D

    170.35 MeV

Solution

The total mass of the initial particles

mi = 1.007825 +7.016004

mi= 8.023829 u

and the total mass of final particles

mf = 2×4.002603 = 8.005206 u

Difference between the initial and final mass of particles

= mi - mf= 8.023829 - 8.005206

= 0.018623 u

The Q value is given by

Q = ∆mc2

= 0.018623×931.5 = 17.35 MeV

Hence, the correct answer is option: 'A'.

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