Question

The pair of atoms having the same number of neutrons is:

• A. ${}_6^{12}C,{}_{12}^{24}Mg$
• B. ${}_{11}^{23}Na,{}_9^{19}F$
• C. ${}_{11}^{23}Na,{}_{12}^{24}Mg$
• D. ${}_{11}^{23}Na,{}_{19}^{39}K$

Answer 1

The correct option is C ${}_{11}^{23}Na,{}_{12}^{24}Mg$

Number of neutons is the difference between atomic number and mass number ($N=A-Z$)

The pair of atoms having the same number of neutrons is $Na,Mg$

The number of neutrons present in sodium is $23-11=12$

The number of neutrons present in Magnesium is $24-12=12$

Hence option C is correct.