Question

Match the followings with their correct expression

• A. ${}^{13}{\text{C}}_4$
• B. ${}^{15}{\text{C}}_6$
• C. ${}^{12}{\text{C}}_3$
• D. ${}^{14}{\text{C}}_5$

Answer 1

Note: ${}^n{\text{C}}_r={}^n{\text{C}}_{(n-r)}$
So,
$\Rightarrow {}^{13}{\text{C}}_9={}^{13}{\text{C}}_{(13-9)}={}^{13}{\text{C}}_4$

$\Rightarrow {}^{15}{\text{C}}_9={}^{15}{\text{C}}_{(15-9)}={}^{15}{\text{C}}_6$

$\Rightarrow {}^{12}{\text{C}}_9={}^{12}{\text{C}}_{(12-9)}={}^{12}{\text{C}}_3$

$\Rightarrow {}^{14}{\text{C}}_9={}^{14}{\text{C}}_{(14-9)}={}^{14}{\text{C}}_5$