A star initially has 1040 deutrons . If produces energy via the process 1H1+1H2→1H3+P and 1H2+1H3→2He4. If the average power radiated by star is 1016W, the deutron supply of star is exhausted in a time of order of
(The masses of nuclei are m(H2)=2.014amu,m(p)=1.007amu,m(n)=1.0084amu,m(H)=4.001amu))