1) A hydrogen atom is an exciting state of principal quantum number (n), it emits a photon of wavelength (λ). when it returns to the ground state. the value of n is A) √λRλR−1 B) √(λR−1)λR C) √λ(R−1) D) √λRλR−1 Answer: Option DExplanation:As 1λ=R(1n21−1n22) ∴ 1λ=R(112−1n2) Mutliply both sides by λ 1=λR(1−1n2)or1λR=1−1n2 or 1n2=1−1λR=λR−1λR or n=√λRλR−1