alleryAn electron and a proton have the same kinetic energy. Which has the larger de Broglie wavelength?
ABoth have equal wavelengths
BThe proton
CThe electron
DNeither has a wavelength
Answer & Solution
Correct answer: C. The electron
1. For same KE: p = √(2 m KE).
2. λ = h/p = h/√(2 m KE).
3. Proton mass ≫ electron mass, so proton momentum is larger for same KE.
4. Larger momentum → smaller wavelength. Electron therefore has the larger λ.
_Source: syllabus Chemistry, Ch 2 "Structure of Atom", §2.6_
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