Question

The triad of the nuclei that is isotonic, is

• A. ${ }_{6} C ^{14},{ }_{7} N ^{14},{ }_{9} F ^{19}$
• B. ${ }_{6} C ^{14},{ }_{7} N ^{15},{ }_{9} F ^{17}$
• C. ${ }_{6} C ^{14},{ }_{7} N ^{14},{ }_{9} F ^{17}$
• D. ${ }_{6} C ^{12},{ }_{7} N ^{14},{ }_{9} F ^{19}$

Answer 1

Answer: (B)

Isotonic species have the same the number of neutrons.
No. of neutrons in
${}_{6} C ^{14}=14-6=8$
${}_7 N ^{14}=14-7=7$
${ }_{9} F ^{19}=19-9=10$
${}_7 N ^{15}=15-7=8$
${ }_{9} F ^{17}=15-7=8$
${ }_{6} C ^{12}=12-6=6$
Hence, ${ }_{6} C ^{14}, 7 N ^{15},{ }_{9} F ^{17}$ are isotonic.