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A star initially has 10^{40} deuterons. It produces energy via the process 

   { }_1 \mathrm{H}^2         +       { }_1 \mathrm{H}^2     \rightarrow         { }_1 \mathrm{H}^3       +      \text { P }    \text { and }

   { }_1 \mathrm{H}^2         +      { }_1 \mathrm{H}^3      \rightarrow          { }_2 \mathrm{He}^4    +      \mathrm{n}

\begin{aligned} & \mathrm{M}\left({ }_2 \mathrm{He}^4\right)=4.0026034, \mathrm{M}(\text { proton })=1.007825, \mathrm{M}(\text { neutron })=1.008665, \\ & \mathrm{M}(\text { deutron })=2.013553,1 \mathrm{eV}=1.6 \times 10^{-19} \mathrm{~J} \end{aligned}

If the average power radiated by the star is 10^{16} \, \, \mathrm{w}, the deuteron supply of the star is exhausted in a time of the order of :

Option: 1

10^6 \mathrm{~s}


Option: 2

10^8 \mathrm{~s}


Option: 3

10^{12} \mathrm{~s}


Option: 4

10^{16} \mathrm{~s}


Answers (1)

best_answer

3 \ { }_{1} \mathrm{H}^2 \rightarrow{ }_2 \mathrm{He}^4+\mathrm{P}+\mathrm{n} \quad \Delta \mathrm{m}=0.0216

             \Rightarrow \mathrm{E}=(\Delta \mathrm{m}) \times 931.4 \mathrm{MeV}

             =3.2 \times 10^{-12} \mathrm{~J}

             \Rightarrow \mathrm{E}_{\text {total }}=\frac{\mathrm{E} \times 10^{40}}{3} \approx 10^{28} \quad \Rightarrow \mathrm{t} \approx \frac{10^{28}}{10^{16}} \approx 10^{12}

Posted by

avinash.dongre

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