Question

An element has atomic number $29$. It belongs to the period $x$ and group $y$. The value of $(2x+y)$ will be:

• A. $20$
• B. $19$
• C. $18$
• D. $21$

Answer 1

The correct option is B $19$

Element has atomic number $29$.
Electronic configuration: $[Ar{]}^{18}3d^{10}4s^1$
Since last electron is in $d$-subshell. Hence element belongs to $d$-block.
In $d$-block: $\text{Group number = Number of}ns\text{electrons}+\text{Number of}(n-1)d\text{electrons}$
Group number $=1+10=11$
Period number$\left(x\right)=$ Valence shell $(n=4)$
Therefore, value of $2x+y=2\times 4+11=19$