Answer:
R₃ = 4.77 x 10⁻¹⁰ m = 0.477 nm
Step-by-step explanation:
In 1913, Neil Bohr proposed an atomic model theory, based upon Quantum theory of radiation. This theory described the atomic structure, removing the defects of Rutherford's Model.
In this theory Bohr also derived the formula for the radius of nth orbit of hydrogen atom. The formula is as follows:
Rn = n²(0.53 x 10⁻¹⁰) m
Where,
Rn = Radius of nth orbit of hydrogen atom
n = no. of orbit
Therefore, for 3rd orbit
n = 3
R₃ = (3)²(0.53 x 10⁻¹⁰) m
R₃ = 4.77 x 10⁻¹⁰ m = 0.477 nm