Q 12 Atomic structure

Q 12 Atomic structure O Two hydrogen atoms collide head on and end up with zero kinetic energy'. Each atom then emits a photon of wavelength 121.6 nm. How fast were the hydrogen atoms travelling before collision? x 106 m/ sec (D) 4.4 x 106 m/ sec (C) 4.4x104 m/ sec (B) 1 Ax 105 m/sec 1. A photon was absorbed by a hydrogen atom in its ground state, and the electron was promoted to the fifth Orbit. When the excited atom returned to its ground state, visible and other quanta were emitted. In this process, radiation of what wavelength must have been emitted? (A) 1.21x10-5cm (B) 1.9x10-e cm (D) 8x10 10 cm (C) 8.23 x 10-8 cm Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atom in the ground state are excited by monochro- mafic light Of energy 12.1 eV. The number of spectral lines emitted by hydrogen according to Bohr's theory will (A) One (B) two (C) Three (D) Four 13. Imagine a hypothetical hydrogen atom with positron in the place of electron. The energy of positron in the first orbit of such a hydrogen atom is (positron is an electron with +ve charge) (B) 12.1 eV (D) insufficient data 14. 15. The correct relation between the circumference of Bohr's orbit and the de Broglie's wavelength is (h' is the principal quantum number) n (A) 2Ttr = 2nx 7tr = n), A particle of charge equal to that of an electron and mass 208 times the mass of the electron moves in a circular orbit around a nucleus of charge +3e. Assuming that the Bohr model of the atom is applicable to this system, of n for which the radius of the orbit is anroximatelv the same as that of the first Bohr orbit

Dear Student,

In this case, the energy of H-atom after it absorbs photon of energy 12.1 eV will be = -13.6 eV + 12.1 eV = -1.5 eV

En=-RH1n2n2=-RHEn=-2.18×10-18 J-1.5×1.6×10-19J=9.08or n = 3

Hence, option (c) is correct.

Best Wishes !

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