Question

Which of the following is a pair of isotones?

• A. ${}_6{C}^{14},{}_6{C}^{12}$
• B. ${}_{16}{S}^{40},{}_{17}C{l}^{40}$
• C. ${}_8^{16}O,{}_8^{17}O$
• D. ${}_6{C}^{14},{}_7{N}^{15}$

Answer 1

The correct option is D ${}_6{C}^{14},{}_7{N}^{15}$

Isotones are species having the same number of neutrons.

$a)In{}_6{C}^{14},\text{number of neutrons}=14-6=8In{}_6{C}^{12},\text{number of neutrons}=12-6=6$

$b)In{}_{16}{S}^{40},\text{number of neutrons = 40 - 16 = 24}In{}_{17}C{l}^{40},\text{number of neutrons = 40 - 17 = 23}$

$c)In{}_8{O}^{16},\text{number of neutrons = 16 - 8 = 8}In{}_8{O}^{17},\text{number of neutrons = 17 - 8 = 9}$

$d)In{}_6{C}^{14},\text{number of neutrons = 14 - 6 = 8}In{}_7{N}^{15},\text{number of neutrons = 15 - 7 = 8}$

Thus, ${}_6{C}^{14}$and${}_7{N}^{15}$ are isotones.