The frequency of line spectrum of sodium is 5.09 x 1014 sec-1. Its wavelength (in nm) will be -[C= 3x108m/sec]

(A) 510nm

(B) 420nm

(C) 589nm

(D) 622nm

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The total number of neutrons in dipositive zinc ions with mass number 70 is -

(A) 34

(B) 40

(C)36

(D) 38

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Number of E/P/N
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With a certain exciting radiation of a particular frequency, to which hydrogen atoms are exposed, the maximum number of spectral lines obtainable in the emission is 15. The uppermost energy level to which the electron is excited is n=

(A) 4

(B) 5

(C) 6

(D) 7

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Hydrogen Spectra
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Consider an electron which is brought close to the nucleus of the atom from an infinite distance, the energy of the electron-nucleus system:

(a) Increases

(b) Decreases

(c) Remains same

(d) None of these

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Bohr
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When accelerated electrons are direct against an anticathode in an X-ray tube, the radiation obtained has a continuous spectrum with a wavelength minimum,

$\lambda$min = (1.24 x 10-6/V) m, where V is the voltage used for accelerating the electrons. Calculate $\lambda$min for V= 5 x 104 volts.

(A) 1.25 Å

(B) 0.75 Å

(C)0.25 Å

(D) 1.00 Å

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Calculate the de Broglie wavelength of an $\alpha$-particle emitted from radium having an energy of 4.8 MeV.

(Mass of $\alpha$-particle=6.6 x 10-24 g; h=Planck's constant = 6.626 x 10-27 erg sec)

(A) 6.18 x 10-13cm

(B) 0.58 x 10-8cm

(C) 6.58 x 10-13cm

(D) 4.12 x 10-11cm

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de Broglie Equation
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An atom forms an ion by the loss of three electrons. The ion has an electronic configuration [Ar]3d6. The symbol of the ion is -

(A) Fe3+

(B) Ni3+

(C) Co3+

(D) Mn+3

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Number of E/P/N
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Using arbitrary energy units we can calculate that 864 arbitrary units (a.u.) are required to transfer an electron in hydrogen atom from the most stable Bohr's orbit to the largest distance from the nucleus

n = $\infty$   E= 0

n = 1 ;   E= -864 Arbitrary units

The energy required to transfer the electron from third Bohr's orbit to the orbit n = $\infty$will be-

(a) 96 Arbitrary units

(b) 192 Arbitrary units

(c) 288 Arbitrary units

(d) 384 Arbitrary units

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Bohr
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The sub-shell that comes after f-sub-sell is called g-subshell. The number of g-sub orbitals in g-sub-shell and the total number of orbitals in the principal orbital respectively are-

(A) 10 and 25

(B) 9 and 25

(C) 11 and 23

(D) 15 and 45

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Shell/Subshell
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The wavelengths of two photons are 2000 Å and 4000 Å respectively. What is the ratio of their energies?

(A) 1/4

(B) 4

(C) 1/2

(D) 2

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