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The spectral lines are closer only when ΔE is large, i.e,λ is small
Two electrons A and B in an atom have the following set of quantum numbers :
A : 3, 2, 2, +1/2, B : 3, 0, 0, +1/2,
Which statement is correct for A and B ?
For A, (n+l) = 5 For B, (n+l) = 3.
Thus, larger is value of (n+l) more is energy level.
Which have the same number of selectrons as the delectrons in Fe^{2+} ?
P has 6 electrons in ssubshells as in dshell of Fe^{2+}.
The desired formulae to calculate nodes.
Mass of H^{+} is minimum.
A characteristic of cathode rays particles (electrons), e/m is constant as electron is fundamental particle
For n = 2; l can have value only 0 and 1, i.e., s and psubshells.
sorbitals being spherical and thus , nondirectional.
In H atom, subshell of a shell posses same energy level, as energy depends only on value of ‘n’
n = 3; l = 1
∴(n + l) = 4
Which set has the same number of unpiared electrons in their ground state?
N and P have 3 unpaired electrons in 2p and 3p respectively; V has 3 unpaired electrons in 3d.
Which statement does not form part of Bohr’s model of the hydrogen atom?
It represent Heisenberg’s uncertainly principle.
The statement are valid for :
(I) in filling a group of orbitals of equal energy it is energetically preferable to assign electron to empty orbitals rather than pair them into a particular orbital.
(II) when two electrons are placed in two different orbitals, energy is lower if the spins are parallel.
Only Hund’s rule discuss filling of electrons in degenerate orbitals.
If E_{1},E_{2} and E_{3} represent respectively the kinetic energies of an electron, an alpha particle and a proton each having same de Broglie wavelength then :
According to de broglie,
The energy level of an orbital in multielectron system depends upon n & l.
The angular speed of the electron in the nth orbit of Bohr hydrogen atom is :
Angular speed is
It is expression to represent angular momentum of an electron in an orbital.
When atoms are bombarded with αparticles, only a few in million of the αparticles suffer deflections, while others pass through undeflected.
It is a fact derived by Rutherford from his a α scattering experiment.
H^{} has two electrons.
What is the correct orbital designation for the electron with the quantum number, n = 4, m = 2, s = 1/2?
l = 3 represent for fsubshell.
The no. of nucleons in O^{16} and O^{18} are 16 and 18 respectively.
Photoelectric emission is observed from a surfcae for frequency v_{1} and v_{2} of the incident radiation (v_{1} > v_{2}). If the maximum kinetic ebergies of the photoelectrons in the two cases are in the ratio 1:k, then the threshold frequency v_{0} is given by :
By eqs. (ii) and (iv),
hv_{2} = hv_{0}khv_{0}+khv_{1}
or v_{0}(1k) = v_{2}kv_{1
}
The radii of two of the first four Bohr’s orbits of the hydrogen atom are in the ratio 1 : 4. The energy difference between them may be:
The two orbits are either I and II or II and IV
When photons of energy 4.25eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy, T_{A} (expressed in eV) and de broglie wavelength,λ_{A}, The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 4.70V is T_{B} = T_{A}  1.50 eV. If the de Broglie wavelength of these photoelectrons is =,λ_{B} = 2λ_{A} then which is not correct?
Let work function of A and B be w_{A }and w_{B} and T_{A}, T_{B} are kinetic energy
∴ 4.25 = w_{A} + T_{A}
or T_{A}=4.25w_{A}
similarly T_{B}=4.70w_{B}
∴ T_{B}T_{A}=0.45+w_{A}w_{B}
1.5=0.45+w_{A}w_{B } (∴T_{B}T_{A}=1.5)
or w_{B}w_{A}= 1.95
∴
∴ (K is kinetic energy)
∴
Also
∴
∴ T_{A}= 2eV T_{B}= 0.5eV w_{A} = 2.25 eV w_{B} = 4.2 eV
Magnetic moment = where n is number of unpaired electrons.
The de Broglie wavelength of a particle with mass 1g and velocity 100m/s is:
= 6.63 * 10^{33}m
The uncertainty in the momentum of an electron is 10^{5} kg m s^{1}. The uncertainty in its position will be:
Use ΔX.ΔP = h/4π
The energy of second Bohr’s orbit in Hatom is 328 kJ mol^{1}, hence the energy of fourth Bohr orbit would be :
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