Question

Atomic number of $Ag$ is $47$. In the same group, the atomic number of elements placed above and below $Ag$ in the long form of periodic table will be $x$ and $y$ respectively. Give the value of $\frac{x+y}{12}$.

• A. $8$
• B. $9$
• C. $10$
• D. $12$

Answer 1

The correct option is B $9$

$Cu$ and $Au$ are the elements lying above and below $Ag$ in the periodic table. In order to get the atomic number of $Au$, add $32$ since it belongs to the $6^{th}$ period (which is having lanthanide elements also). To get the atomic number of $Cu$, subtract $18$ from the atomic number of $Ag$ since $Cu$ belongs to the $4^{th}$ period in the periodic table.
$Cu=47-18=29\left(x\right)$
$Au=47+32=79\left(y\right)$
The value of $\frac{x+y}{12}=\frac{29+79}{12}=9$