Velocity of electron moving in first orbit of hydrogen is:
Correct answer: D. 2.19 x 10^6 m/sec
- A. 2.19 x 10^7 m/sec
- B. 2.18 x 10^7 m/sec
- C. 2.2 x 10^8 m/sec
- D. 2.19 x 10^6 m/sec
Explanation
The velocity of an electron in the first orbit of hydrogen can be calculated using the Bohr model formula: v = n × h / (2π × m × r), where: n is the principal quantum number (1 for the first orbit), h is Planck's constant (6.63 × 10-34 Js), m is the mass of the electron (9.1 × 10-31 kg), r is the radius of the orbit (0.529 × 10-10 m). Substituting these values gives a velocity of approximately 2.19 × 106 m/s. The other options are incorrect as they either exceed feasible values or are too high for the first orbit.
This question appeared on the UHS MDCAT 2010 paper, which you can sit online with every answer explained.
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