Question

Identify the correct pair of isobars.

• A. ${}_6$C${}^{12}$, ${}_6$C${}^{13}$
• B. ${}_{11}$Na${}^{24}$, ${}_{12}$Mg${}^{24}$
• C. ${}_8$O${}^{16}$, ${}_8$O${}^{17}$
• D. ${}_6$C${}^{14}$, ${}_7$N${}^{14}$

Answer 1

The correct option is B ${}_{11}$Na${}^{24}$, ${}_{12}$Mg${}^{24}$

Isobars are elements having the same mass number, but different atomic numbers.

Amongst the given pairs, sodium (Na) and magnesium (Mg) has the same mass number (A = 24). Atomic number of Na is 11 and that of Mg is 12, thereby making them a pair of isobars.

Option A is not correct as it represents isomers which belong to the same element. Isobars always are different elements.