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A compound of vandanium has a magnetic moment
of 1.73 BM. Write the electronic configuration of
Vandium in this compound.
1. [Ar] 4s² 3d³
2. [Ar] 4s¹ 3d³
3. [Ar] 3d²
4. [Ar] 3d¹

for frequencies v1 and v2 of the incident radiations
(v₁ > v₂). If the maximum kinetic energy of the
photoelectrons in two cases are in the ratio 1 : K,
then the threshold frequency v₀ is given by
1. $\frac{{\mathrm{v}}_2-{\mathrm{v}}_1}{\mathrm{K}-1}$
2. $\frac{{\mathrm{Kv}}_1-{\mathrm{v}}_2}{\mathrm{K}-1}$
3. $\frac{{\mathrm{Kv}}_2-{\mathrm{v}}_1}{\mathrm{K}-1}$
4. $\frac{{\mathrm{v}}_2-{\mathrm{v}}_1}{\mathrm{K}}$

An electron in an atom jumps in such a way that its
kinetic energy changes from x to x/4. The change in
potential energy will be
1. $+\frac{3}{2}\mathrm{x}$
2. $-\frac{3}{8}\mathrm{x}$
3. $+\frac{3}{4}\mathrm{x}$
4. $-\frac{3}{4}\mathrm{x}$

The distance between 4th and 3rd Bohr orbits of ${\mathrm{He}}^{+}$
is
1. 2.645 × 10^–10
2. 2.322 × 10^–10
3. 1.851 × 10^–10
4. None of these

Electronic transition in He⁺ ion takes from n₂ to n₁
shell such that:
2n₂ + 3n₁ = 18
2n₂ – 3n₁ = 6
What will be the total number of photons emitted
when electrons transit to n₁ shell?
1. 21
2. 15
3. 20
4. 10

According to Einstein’s photoelectric equation, the
graph between kinetic energy photoelectrons ejected
and the frequency of the incident radiation is:

If ${\mathrm{\lambda }}_0$ and $\mathrm{\lambda }$ be the threshold wavelength and the
wavelength of incident light, the speed of photoelectron
ejected from the metal surface is
1. $\sqrt{\frac{2\mathrm{h}}{\mathrm{m}}\left({\mathrm{\lambda }}_0-\mathrm{\lambda }\right)}$
2. $\sqrt{\frac{2\mathrm{hc}}{\mathrm{m}}\left({\mathrm{\lambda }}_0-\mathrm{\lambda }\right)}$
3. $\sqrt{\frac{2\mathrm{hc}}{\mathrm{m}}\left(\frac{{\mathrm{\lambda }}_0-\mathrm{\lambda }}{{\mathrm{\lambda }}_0\mathrm{\lambda }}\right)}$
4. $\sqrt{\frac{2\mathrm{hc}}{\mathrm{m}}\left(\frac{1}{{\mathrm{\lambda }}_0}-\frac{1}{\mathrm{\lambda }}\right)}$

Which of the folowing orbitals has two spherical
nodes?
1. 2s
2. 4s
3. 3d
4. 6f

An electron is allowed to move freely in a closed cubic box of length of side 10 cm. The maximum uncertainty in its velocity will be :
1. $3.35\times {10}^{-3} \mathrm{m} {\sec }^{-1}$
2. $5.8\times {10}^{-4} \mathrm{m} {\sec }^{-1}$
3. $4\times {10}^{-5} \mathrm{m} {\sec }^{-1}$
4. $4\times {10}^{-6} \mathrm{m} {\sec }^{-1}$

An element undergoes a reaction as shown :
$\mathrm{X}+2{\mathrm{e}}^{-}\to {\mathrm{X}}^{2-}$, energy released = 30.87 eV/atom. If the energy released, is used to dissociate 4 gms of H₂ molecules, equally into ${\mathrm{H}}^{+ }\mathrm{and} {\mathrm{H}}^{*}$ where ${\mathrm{H}}^{*}$ is excited state of atoms where the electron travels in orbit whose circumference equal to four times its De-Broglie wavelength. Determine the least moles of X that would be required :
Given : I.E. of H = 13.6 eV/atom, bond energy of  H₂ = 4.526 eV/molecule
1. 1
2. 2
3. 3
4. 4 

If in Bohr's model, for unielectron atom, time period of revolution is represented as ${\mathrm{T}}_{\mathrm{n},\mathrm{Z}}$ where n represents shell no. and Z represents atomic number tham the value of ${\mathrm{T}}_{1,2}:{\mathrm{T}}_{2,1}$ will be 
1. 8:1
2. 1:8
3. 1:1
4. 1:32