Question

Which of the following elements does not belong to the same period?
${}_8^{16}\text{P}{,}_9^{19}\text{Q}{,}_{10}^{20}\text{R}and{}_{11}^{23}\text{S}$

• A. ${}_8^{16}\text{P}$
• B. ${}_9^{19}\text{Q}$
• C. ${}_{10}^{20}\text{R}$
• D. ${}_{11}^{23}\text{S}$

Answer 1

The correct option is D ${}_{11}^{23}\text{S}$

P, Q and R belongs to second period but S belongs to 3rd period.