Assuming that about `20 MeV` of energy is released per fusion reaction
`._1H^2 +._1 H^2 rarr. _2He^3 + E +` other particles then the mass of `._1H^2` consumed per day in a fusion reactor of power `1` megawatt wil approximately be.

Options

A. `0.001 g`
B. `0.1 g`
C. `10.0 g`
D. `1000 g`

Answer

B

Explanation

(b) `P = 10^6` watt
Time `= 1 day = 24 xx 36 xx 10^6 sec`
Energy produced,
`U = P_t = 10^6 xx 24 xx 36 xx 10^2`
` =24 xx 36 xx 10^8` Joule
Energy released per fusion reaction
`= 20 MeV`
`=32 xx 10^-13` Joule
Energy released per atom of `._1 H^2`
`=32 xx 10^-13` Joule
Number of `._1 H^2` atoms used
`=(24 xx 36 xx 10^8)/(32 xx 10^-13) = 22 xx 10^21`
Mass of `6 xx 10^23` atoms `= 2g`
`:.` Mass `27 xx 10^21` atoms
`=(2)/(6 xx 10^23) xx 27 xx 10^21 = 0.1 g`.