Electronic
configuration of species M^{2+} is 1s^{2} 2s^{2} 2p^{6}
3s^{2} 3p^{6} 3d^{6} and its atomic weight is 56. The
number of neutrons in the nucleus of species M is

**A. ** 26

**B. ** 22

**C. ** 30

**D. ** 24

**Answer : ****Option C**

**Explaination / Solution: **

M^{2+} : 1s^{2} 2s^{2} 2p^{6}
3s^{2} 3p^{6} 3d^{6}

M : 1s^{2} 2s^{2} 2p^{6} 3s^{2}
3p^{6} 3d^{8}

Atomic number = 26

Mass number =56

No. of neutrons = 56 -26 = 30

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The
energy of light of wavelength 45 nm is

**A. ** 6.67 × 10^{15}J

**B. ** 6.67 × 10^{11}J

**C. ** 4.42 × 10^{–18}J

**D. ** 4.42 × 10_{–15}J

**Answer : ****Option C**

**Explaination / Solution: **

E = hν = hc/λ

=6.626 × 10^{}^{34} J s × 3 ×10^{8}
m s^{}^{1 } /_{ }45 ×10^{}^{9} m

= 4 .42 ×10^{}^{18} J_{}

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The
energies E_{1} and E_{2} of two radiations are 25 eV and 50 eV
respectively. The relation between their wavelengths ie λ_{1} and λ_{2}
will be

**A. ** λ_{1}/λ_{2}
= 1

**B. ** λ_{1}
= 2λ_{2}

**C. ** λ_{1}
= √(25 × 50 λ_{2})

**D. ** 2λ_{1}
= λ_{2}

**Answer : ****Option B**

**Explaination / Solution: **

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Splitting of spectral
lines in an electric field is called

**A. ** Zeeman effect

**B. ** Shielding effect

**C. ** Compton effect

**D. ** Stark effect

**Answer : ****Option D**

**Explaination / Solution: **

Spliting of spectral lines in magnetic field is
called Zeeman effect and spliting of spectral lines in electric field, is
called Stark effect.

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Based
on equation E = – 2.178 × 10^{–18} J (z^{2}/n^{2})
certain conclusions are written. Which of them is not correct ?

**A. ** Equation
can be used to calculate the change in energy when the electron changes orbit

**B. ** For
n = 1, the electron has a more negative energy than it does for n = 6 which
means that the electron is more loosely bound in the smallest allowed orbit

**C. ** The
negative sign in equation simply means that the energy of electron bound to the
nucleus is lower than it would be if the electrons were at the infinite
distance from the nucleus.

**D. ** Larger
the value of n, the larger is the orbit radius.

**Answer : ****Option B**

**Explaination / Solution: **

**Correct statement: **For n=1, the**
**electron has more negative energy than it does for n=6 which means that the
electron is **strongly** bound in the
smallest allowed orbit.

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According
to the Bohr Theory, which of the following transitions in the hydrogen atom
will give rise to the least energetic photon ?

**A. ** n =
6 to n = 1

**B. ** n =
5 to n = 4

**C. ** n =
5 to n = 3

**D. ** n =
6 to n = 5

**Answer : ****Option D**

**Explaination / Solution: **

n = 6 to n=5

E_{6} = -13.6 / 6^{2} ;

E_{5} = - 13.6 / 5^{2}

E_{6} - E_{5} = (-13.6 /6^{2})
- (-13.6/5^{2})

= 0.166 eV atom^{-1}

E_{5} - E_{4} = (-13.6 /5^{2})
- (-13.6/4^{2})

= 0.306 eV atom^{-1}

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Assertion : The spectrum of He^{+} is expected
to be similar to that of hydrogen

No Explaination.

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Which
of the following pairs of d-orbitals will have electron density along the axes
?

**A. ** d_{z}2,
d_{xz}

**B. ** d_{xz},
d_{yz}

**C. ** d_{z}2,
d_{x}2_{-y}2

**D. ** d_{xy},
d_{x}2_{-y}2

**Answer : ****Option C**

**Explaination / Solution: **

No Explaination.

No Explaination.

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Two
electrons occupying the same orbital are distinguished by

**A. ** azimuthal
quantum number

**B. ** spin
quantum number

**C. ** magnetic
quantum number

**D. ** orbital
quantum number

**Answer : ****Option B**

**Explaination / Solution: **

Spin quantum number

For the first electron m_{s} = +½

For the second electron m_{s} = -½

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The
electronic configuration of Eu (Atomic no. 63) Gd (Atomic no. 64) and Tb (Atomic
no. 65) are

**A. ** [Xe]
4f^{6} 5d^{1} 6s^{2}, [Xe] 4f^{7} 5d^{1}
6s^{2} and [Xe] 4f^{8} 5d^{1} 6s^{2}

**B. ** [Xe]
4f^{7} , 6s^{2}, [Xe] 4f^{7} 5d^{1} 6s^{2}
and [Xe] 4f^{9} 6s^{2}

**C. ** [Xe]
4f^{7} , 6s^{2}, [Xe] 4f^{8} 6s^{2} and [Xe] 4f^{8}
5d^{1} 6s^{2}

**D. ** [Xe]
4f^{6} 5d^{1} 6s^{2}, [Xe] 4f^{7} 5d^{1}
6s^{2} and [Xe] 4f^{9} 6s^{2}

**Answer : ****Option B**

**Explaination / Solution: **

Eu : [Xe] 4f^{7}, 5d^{0}, 6s^{2}

Gd : [Xe] 4f^{7}, 5d^{1}, 6s^{2}

Tb: [Xe] 4f^{9}, 5d^{0}, 6s^{2}

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