Answer:
Xenon, Xe
Step-by-step explanation:
Atomic number of Zr = 40
Electronic configuration of Zr =
![[Kr] 4d^2 5s^2](https://img.qammunity.org/2020/formulas/chemistry/middle-school/gdedjqzrggpke434wjcwpo4worrtrww2w0.png)
As last electron enters in 5th shell, therefore, Zr belongs to period 5.
The noble gas which present in 5th period is Xe.
Atomic number of Xenon = 54
Electronic configuration of Xe =
![[Kr] 4d^2 5s^25p^6](https://img.qammunity.org/2020/formulas/chemistry/middle-school/mk0a9vgw7pb9xlbr6n7kbes7u3sg9x96so.png)
So, Xe also belongs to period 5