Neco 2019 Physics Question 20

Practice objective / multiple choice question 20 from the 2019 Neco Physics examination.

Neco 2019 Physics Objective / Multiple Choice Hard Difficulty

Question 20 NECO • 2019 • PHYSICS • objective

A hydrogen atom makes a transition from the \(n = 5\) level to the \(n = 2\) level, emitting a photon. The photon is incident on a diffraction grating that has \(1.15 \times 10^{6}\) lines per metre. In the first‑order (\(m = 1\)) spectrum the maximum is observed at an angle of \(30^{\circ}\). (i) Find the wavelength of the photon in nanometres. (ii) Determine the energy of the photon in electron‑volts. (iii) Assuming the hydrogen atom was initially at rest and neglecting other forces, calculate the recoil speed of the atom after the emission (give the speed in \(\text{m s}^{-1}\) to two significant figures).

A. 425 nm, 2.75 eV, 0.78 m\/s

B. 440 nm, 2.80 eV, 0.85 m\/s

C. 430 nm, 2.90 eV, 0.95 m\/s

Correct Answer D. 435 nm, 2.86 eV, 0.91 m/s

Correct Answer

Correct Option:

435 nm, 2.86 eV, 0.91 m/s

This is Neco 2019 Physics Question 20. It is one of the objective questions from the 2019 Neco Physics examination.

Difficulty level: Hard .

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