Q276 · Practice questionComplex familiar3 marks
QUESTION 276 (3 marks)
Hydrogen emits photons when electrons end at . Use .
a)[2 marks]
Calculate the limiting wavelength as the initial principal quantum number becomes very large.
b)[1 mark]
Explain whether a 350 nm photon can be emitted in a bound-to-bound transition ending at n = 2.
WORKED SOLUTION
3 marksPractice marking scheme
ANSWER
(a) (about ). (b) No; it is shorter than the series limit.
Worked solution
(a) . Therefore .
(b) Every finite initial bound state gives a smaller energy difference and a longer wavelength than the limiting transition.
Equivalent physically justified methods, alternative valid sketches and consistent units accepted.
Accept sensible significant figures and consistent rounding from stated constants.
Part a: Take the limit of the initial-state term.
Part a: Calculate the limiting wavelength.
Part b: Reject 350 nm using its position below the limiting wavelength or above the maximum allowed energy gap.
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
View the QCAA syllabusHow many marks did you earn?
Compare your working with the guide above.