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NCERT Class XI Chemistry Structure of Atom Solutions

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Question : 59 of 67
Marks: +1, -0
If the velocity of the electron in Bohr’s first orbit is 2.19 × 106ms110^{6}\,\mathrm{m}\,\mathrm{s}^{-1}, calculate the de Broglie wavelength associated with it.
Solution:  
We know that, λ = hmv\frac{h}{mv} where, h = 6.626 × 103410^{-34} J s,
m = mass of electron = 9.1 × 1031kg10^{-31}\,\mathrm{kg}, v = 2.19 × 106m/s10^{6}\,\mathrm{m/s}
∴ λ = 6.626×10349.1×1031×2.19×106\frac{6.626 \times 10^{-34}}{9.1 \times 10^{-31} \times 2.19 \times 10^{6}} = 0.32 × 109m10^{-9}\,\mathrm{m} = 332 × 1012m10^{-12}\,\mathrm{m}
λ = 332 pm [Since 1 pm = 1012m10^{-12}\,\mathrm{m}]
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