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MCQ

Question

An electron in Li²⁺ has a de Broglie wavelength of 2.21 × 10⁻¹⁰ m in the second orbit. What is its kinetic energy? (h = 6.626 × 10⁻³⁴ J s, mₑ = 9.1 × 10⁻³¹ kg)

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2.18 × 10⁻¹⁸ J 9.872 × 10⁻¹⁸ J 1.234 × 10⁻¹⁸ J 4.936 × 10⁻¹⁸ J Correct

v = h/(mλ). KE = ½mv² = 4.936×10⁻¹⁸ J.

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