Pre Video Test: Structure of atomContact Number: 9667591930 / 8527521718

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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] 4s^{2} 3d^{3 }

2. [Ar] 4s^{1} 3d^{3}

3. [Ar] 3d^{2 }

4. [Ar] 3d^{1}

for frequencies v1 and v2 of the incident radiations

(v_{1} > v_{2}). If the maximum kinetic energy of the

photoelectrons in two cases are in the ratio 1 : K,

then the threshold frequency v_{0} 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

According to Bohr’s atomic theory, which of the

following reaction is correct?

1. Potential energy of electron ∝ $\frac{{\mathrm{Z}}^{2}}{{\mathrm{n}}^{2}}$

2. The product of velocity of electron and principal

quantum number (n) ∝ Z^{2}

3. Frequency of revolution of electron in an orbit ∝ $\frac{{Z}^{3}}{{n}^{3}}$

4. Coulombic force of attraction on the electron ∝ $\frac{{Z}^{2}}{{n}^{2}}$

Electronic transition in He^{+} ion takes from n_{2} to n_{1}

shell such that:

2n_{2} + 3n_{1} = 18

2n_{2} – 3n_{1} = 6

What will be the total number of photons emitted

when electrons transit to n_{1} shell?

1. 21

2. 15

3. 20

4. 10

Which of the following electron transitions in a

hydrogen atom will require the largest amount of

energy?

1. from n = 1 to n = 2

2. from n = 2 to n = 4

3. from n = 5 to n = 1

4. from n = 3 to n = 5

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. $\sqrt{\frac{2\mathrm{hc}}{\mathrm{m}}\left(\frac{1}{{\mathrm{\lambda}}_{0}}-\frac{1}{\mathrm{\lambda}}\right)}$

If a_{0} be the radius of first Bohr’s orbit of H-atom, the

de-Broglie’s wavelength of an electron revolving the

second Bohr’s orbit will be:

1. 6 $\mathrm{\pi}$a_{0}

2. 4 $\mathrm{\pi}$a_{0}

3. 2 $\mathrm{\pi}$a_{0}

4. None of these

The ratio of magnetic moment of Fe (III) and Co (II)

is

1. $\sqrt{5}:\sqrt{7}$

2. $\sqrt{35}:\sqrt{15}$

3. 7:3

4. $\sqrt{24}:\sqrt{15}$

The variation of radial probability density R2(r) as a

function of distance r of the electron from the nucleus

for 3p-orbital :

The subshell that arises after f is called the g subshell.

How many electrons may occupy that g subshell?

1. 9

2. 7

3. 5

4. 18

Which of the folowing orbitals has two spherical

nodes?

1. 2s

2. 4s

3. 3d

4. 6f

Wave function of an orbital is plotted against the

distance from nucleus. The graphical representation

is of

1. 1s

2. 2s

3. 3s

4. 2p

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