Question

1. choose the correct electron configuration for the element. refer to the periodic table. he xe 2s² 1s² ne 1s² 2s² 18) choose the correct electron configuration for the element. refer to the periodic table. po xe 6s²4f¹⁴5d¹⁰6p⁴ xe 6s²4f¹⁴5d¹⁰6p² xe 6s² xe 6s²4f¹⁴5d⁷

Explanation:

For question 17 (He):

Helium has 2 electrons. The electron configuration uses the noble gas shorthand; since it is a noble gas itself, its full configuration is $1s^2$, which matches the correct option.

For question 18 (Po):

Polonium (Po) has an atomic number of 84. Xenon (Xe) is the preceding noble gas with 54 electrons. The remaining 30 electrons fill the orbitals in order: $6s^2$, $4f^{14}$, $5d^{10}$, $6p^4$, so the shorthand configuration is $[Xe] 6s^24f^{14}5d^{10}6p^4$.

Answer:

1. $1s^2$
2. $[Xe] 6s^24f^{14}5d^{10}6p^4$