Emission and Absorption Spectra

Q.

In a Bohr's model of atom when an electron jumps from n=1 to n=3, how much energy will be emitted or absorbed

1. 2.15 X 10^-11 erg

2. 0.1911 X 10^-10 erg

3. 2.389 X 10^-12 erg

4. 0.239 X 10^-10 erg

Q.

The energy of an electron in the first Bohr orbit of H atom is -13.6eV. The possible energy value(s) of the excited state(s) for electrons in Bohr orbits to hydrogen is(are)

1. -3.4eV

2. -4.2eV

3. -6.8eV

4. +6.8eV

Q.

The maximum kinetic energy of the photoelectrons is found to be $6.63\times {10}^{-19}J$. When the metal is irradiated with a radiation of frequency $2\times {10}^{15}Hz$, the threshold frequency of the metal is about

1. 1 × 10¹⁵ S^-1

2. 2 × 10¹⁵ S^-1

3. 3 × 10¹⁵ S^-1

4. 105×10¹⁵ S^-1

Q. Values of n, l, m and s for electron 4s1 orbital will be

Q. 34.Why is energy of 2s orbital of hydrogen atom is greater than the 2s orbital of lithium atom ?

Q. when the surface of the metal is irradiated by applying the radiation of wavelength 400A, the ejected electron travels with KE\:two third of the incident energy. find the stopping potential of the photoelectron ejected

Q.

Zeeman effect is the splitting of spectral line in presence of:

1. electricity

2. magnetic effect

3. molecule

4. electric field

Q. The angular momentum of an electron in first excited state of hydrogen atom is

1. $3\hslash$
2. $2\hslash$
3. $\frac{\hslash }{2}$
   
4. $\hslash$

Q.

The frequency of one of the lines in Paschen series of hydrogen atom is $2.750\times {10}^{14}$ Hz. The quantum number which produces this transition is:

1. n=2

2. n=4

3. l=2

4. n=6

Q. The limiting line of Paschen series of H atom will have a frequency equal to:
$R=1.097\times {10}^7{\text{m}}^{-1}$

1. $3.65\times {10}^{14}$ Hz
2. $3.65\times {10}^{16}$ Hz
3. $4.95\times {10}^{17}$ Hz
4. $3.63\times {10}^{12}$ Hz

Q. What is the maximum wavelength line in the Lyman series for $H{e}^{+}$ ion?

1. $3R$
2. $\frac{1}{3R}$
3. $\frac{4}{4R}$
4. None of these

Q. What electronic transition in the $H{e}^{+}$ spectrum would have the same wavelength as the first Lymen transition of hydrogen:-

1. n = 4 to n = 2
2. n = 1 to n = 4
3. n = 4 to n = 3
4. n = 3 to n = 4

Q.

All of the orbitals in a given electron shell can have the same value of the quantum number except

1. Principal

2. Azimuthal

3. Magnetic

4. Spin

Q.

The wave number range of microwaves are greater than

1. ${10}^2{m}^{-1}$
2. ${10}^6{m}^{-1}$
3. ${10}^8{m}^{-1}$
4. All of the above

Q. How many spectral lines are produced, when an electron jumps from n = 5 to ground state (n=1)?

1. 10
2. 5
3. 26
4. 14

Q. Which of the following statement(s) are wrong?

1. Photons having energy $400\text{kJ}$ will break 4 mole bonds of a molecule $A_2$ where $A-A$ bond dissociation energy is $100\text{kJ/mol}$
2. Two bulbs are emitting light having wavelength $2000\stackrel{\circ }{A}$ and $3000\stackrel{\circ }{A}$ respectively. If the bulbs $A$ and $B$ are 40 watt and 30 watt respectively then the ratio of no. of photons emitted by $A$ and $B$ per day is $1:2$
3. When an electron makes transition from lower to higher orbit, photon is emitted
4. None of the above

Q.

The spectrum of He is expected to be similar to

1. H

2. Li⁺

3. Na

4. He⁺

Q.

Which one of the following is an incorrect orbital notation?

1. 3f

2. 3d

3. 2s

4. 3p

Q. Calculate the energy of radiation emitted for the electronic transition from infinity to ground state for $L{i}^{2+}$ ion.
$(\text{Given}:c=3\times {10}^8\text{m/s},R_H=1.09678\times {10}^7{\text{m}}^{-1}$
$h=6.626\times {10}^{-34}{\text{J s}}^{-1})$

1. $19.66\times {10}^{-18}\text{J}$
2. $17.66\times {10}^{-18}\text{J}$
3. $9.83\times {10}^{-18}\text{J}$
4. $8.83\times {10}^{-18}\text{J}$

Q. An electron makes a transition from $7^{th}$ excited state to $2^{nd}$ energy level in a $H$-atom sample. Find the maximum spectral lines observed.

1. $15$
2. $21$
3. $23$
4. $17$

Q. Why line spectrum is FINGERPRINT OF AN ATOM?

Q. Find energy of each of the photons which
(i) correspond to light of frequency $3\times {10}^{15}Hz$.
(ii) have wavelength of $0.50\stackrel{\circ }{A}$.

Q. 1 Which is most electronegative orbital. 1.s 2 sp

Q. When photon of energy 4.25eV strikes the surface of metal A the ejected photoelectrons have a maximum kinetic energy, Ta and de broglie wavelength A. The maximum kinetic energy of photoelectrons liberated from another metalB by photon of energy 4.70 eV is Tb =Ta-1.50eV. If the de broglie wavelength of these photoelectrons is waveleght of B =2 wavelength of A then which is not correct (A) the work function of A is 2.25ev (B) the work function of B is 1.20 ev (C) Ta=2.00ev (D) Tb= 0.5 ev

Q.

Given the value of Rydberg Constant is ${10}^{-7}{m}^{-1}$, the wave number of last line of the Balmer series in hydrogen spectrum will be:

Q. In Bohr series of lines of hydrogen spectrum, the third line from the red end corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen?

1. $3\to 2$
2. $5\to 2$
3. $4\to 1$
4. $2\to 5$

Q. 72. A photon of wavelength 4×10 to the power -7m strikes on metal surface, the work function of the metal being 2.13 event. Calculate (i) energy of photon(ev), (ii) kinetic energy of emission, and (iii) velocity of photo electron (1ev=1.6020×10to the power -19 joule.

Q. Total number of electrons present in a calcium atom having $(n+\ell )=4$ is

1. $9$
2. $6$
3. $8$
4. $10$

Q. The spectral series of $H-$ atom gives ${\overline{v}}_{\text{min}}$ and ${\overline{v}}_{\text{max}}$ depending on the types of transition. Which of the following is/are true?

1. $\begin{array}{ccc}\text{Series name}& {\overline{v}}_{\text{max}}& {\overline{v}}_{\text{min}}\\ \text{Lyman}& {\overline{R}}_H& \frac{3}{4}{\overline{R}}_H\end{array}$
2. $\begin{array}{ccc}\text{Series name}& {\overline{v}}_{\text{max}}& {\overline{v}}_{\text{min}}\\ \text{Balmer}& \frac{{\overline{R}}_H}{4}& \frac{5}{36}{\overline{R}}_H\end{array}$
3. $\begin{array}{ccc}\text{Series name}& {\overline{v}}_{\text{max}}& {\overline{v}}_{\text{min}}\\ \text{Paschen}& \frac{{\overline{R}}_H}{9}& \frac{7}{144}{\overline{R}}_H\end{array}$
4. $\begin{array}{ccc}\text{Series name}& {\overline{v}}_{\text{max}}& {\overline{v}}_{\text{min}}\\ \text{Brackett}& \frac{{\overline{R}}_H}{16}& \frac{9}{400}{\overline{R}}_H\end{array}$

Q. Calculate the wavelength of a photon that is emitted when an electron in the Bohr orbit $n=2$ returns to the orbit $n=1$ in a $H{e}^{+}$ ion.
The ionisation potential of the ground state $H{e}^{+}$ ion is $8.68\times {10}^{-11}\text{erg per atom}$.

1. $205\stackrel{o}{\text{A}}$
2. $255\stackrel{o}{\text{A}}$
3. $305\stackrel{o}{\text{A}}$
4. $355\stackrel{o}{\text{A}}$