Question

Oxygen consists of isotopes ${\text{O}}^{16}$,${\text{O}}^{17}$ and ${\text{O}}^{18}$ carbon consists of isotopes of ${\text{C}}^{\text{12}}$ and ${\text{C}}^{\text{13}}$ Total number of $\text{C}{\text{O}}_2$ molecules possible are

• A. 6
• B. 12
• C. 18
• D. 1

Answer 1

Answer: (B)

12

As there are $3$ isotopes of $O$ and $2$ isotpes of $C$, So based on permulation and combination

Total number of combinations are $3!2!$

$3\times 2\times 1\times 2\times 1$

$=3\times 2\times 2$

$=12$