Question

In carbon cycle of fusion, 4 protons combine to yield one alpha particle and

• A. one positron
• B. two positrons
• C. ten positrons
• D. three positrons

Answer 1

Answer: (B)

two positrons

Carbon cycle [Carbon - Nitrogen Cycle] :
It consists of following reactions :
${}_6^{12}C{+}_1^{1}H{\Rightarrow }_7^{13}N+Q_1$
${}_7^{13}N{\Rightarrow }_6^{13}C+{(}_1^{0}e)+Q_2$
${}_6^{13}C{+}_1^{1}H{\Rightarrow }_7^{14}N+Q_3$
${}_7^{14}N{+}_1^{1}H{\Rightarrow }_8^{15}O+Q_4$
${}_8^{15}O{\Rightarrow }_7^{15}N+{(}_1^{0}e)+Q_5$
${}_7^{15}N{+}_1^{1}H{\Rightarrow }_6^{12}C{+}_2^{4}He+Q_6$
On adding all these equations, we get
$4_1^{1}H{\to }_2^{4}He+2{(}_1^{0}e)+Q$
(proton) ($\alpha -$ particle) (positron) (energy)
where, $Q=Q_1+Q_2+Q_3+Q_4+Q_5+Q_6$ the value of Q as calculated from mass defect is 26.7 MeV.