02 MeV
(ii)
2
1
3
1
1
2
H
H
He
+
→
+ g + 5 49 MeV
(iii)
+
→
+
+
3
3
4
1
1
2
2
2
1
1
He 
He 
He
H
H + 12 86 MeV (iv)
(13 14)
For the fourth reaction to occur, the first three reactions must occur
twice, in which case two light helium nuclei unite to form ordinary helium
nucleus