Question

Fill in the blank:

In the carbon cycle, from which stars, hotter than the Sun, obtain their energy, the ${}_6{C}^{12}$ isotope ______.

• A. splits up into three alpha particles
• B. fuses with another ${}_6{C}^{12}$ nucleus to form ${}_{12}M{g}^{24}$
• C. is completely converted into energy
• D. is regenerated at the end of the cycle

Answer 1

The correct option is D is regenerated at the end of the cycle

Carbon cycle :

${}_6^{12}C{+}_1^{1}H{\to }_7^{13}N+Q_1$

${}_7^{13}N{\to }_6^{13}C+{(}_1^{0}e)+Q_2$

${}_6^{13}C{+}_1^{1}H{\to }_7^{14}N+Q_3$

${}_7^{14}N{+}_1^{1}H{\to }_8^{15}O+Q_4$

${}_8^{15}O{\to }_7^{15}N+{(}_1^{0}e)+Q_5$

${}_7^{15}N{+}_1^{1}H{\to }_6^{12}C{+}_2^{4}He+Q_6$

So, in the final reaction Carbon is regenerated.