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Which statement relating to the spectrum of H atom is false?
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 s-electrons as the d-electrons in Fe2+ ?
P has 6 electrons in s-subshells as in d-shell of Fe2+.
The statements, which is/are correct:
The desired formulae to calculate nodes.
Which has highest e/m ratio?
Mass of H+ is minimum.
The ratio of e/m, i.e., specific charge for a cathode ray :
A characteristic of cathode rays particles (electrons), e/m is constant as electron is fundamental particle
Which is not permissble subshell?
For n = 2; l can have value only 0 and 1, i.e., s and p-subshells.
Non-directonal orbital is :
s-orbitals being spherical and thus , non-directional.
In hydrogen atom, which energy level order is not correct :
In H atom, subshell of a shell posses same energy level, as energy depends only on value of ‘n’
The n+l value for the 3p-energy level is :
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.
Which best describe the emission spectra of atomic hydrogen?
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 E1,E2 and E3 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,
A quanta will have more energy, if :
Which of the following statement is not correct?
The energy level of an orbital in multi-electron system depends upon n & l.
The angular speed of the electron in the nth orbit of Bohr hydrogen atom is :
Angular speed is
Angular momentum of an electron in an orbital is given by :
It is expression to represent angular momentum of an electron in an orbital.
When atoms are bombarded with α-particles, only a few in million of the α-particles suffer deflections, while others pass through undeflected.
It is a fact derived by Rutherford from his a α- scattering experiment.
Electronic configuration of H- is :
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 f-subshell.
The ratio of nucleons in O16 and O18 is :
The no. of nucleons in O16 and O18 are 16 and 18 respectively.
Photoelectric emission is observed from a surfcae for frequency v1 and v2 of the incident radiation (v1 > v2). If the maximum kinetic ebergies of the photoelectrons in the two cases are in the ratio 1:k, then the threshold frequency v0 is given by :
By eqs. (ii) and (iv),
hv2 = hv0-khv0+khv1
or v0(1-k) = v2-kv1
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, TA (expressed in eV) and de broglie wavelength,λA, The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 4.70V is TB = TA - 1.50 eV. If the de Broglie wavelength of these photoelectrons is =,λB = 2λA then which is not correct?
Let work function of A and B be wA and wB and TA, TB are kinetic energy
∴ 4.25 = wA + TA
or wB-wA= 1.95
∴ (K is kinetic energy)
∴ TA= 2eV TB= 0.5eV wA = 2.25 eV wB = 4.2 eV
Which ion has the maximum magnetic moment?
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 * 10-33m
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 H-atom is -328 kJ mol-1, hence the energy of fourth Bohr orbit would be :