Answer:
= 4
Explanation:
To solve this exercise we will use Bohr's atomic model
= - 13.606 / n² [eV]
The transition from level n = 2 to level n = 1 is valid
= - 13.606 [¼ -1/1]
= 10.2045 eV
Bohr's model for atoms with only one electron is
= -13.606 Z² / n²
Where Z is the atomic number of the atom.
In this case the helium atom has an atomic number of Z = 2 from the level n₀ = 2 let's look up to what level it reaches
ΔE = -13.606 [4 / ² - 4/4]
4 / ² = -ΔE / 13.606 + 1
4 / ² = -10.2045 / 13.606 +1 = -0.75 +1
4 / ² = 0.25
= √ 4 / 0.25
= 4