Planck's Quantum Hypothesis

Q.

What is the number of photons of light with a wavelength of 4000 pm that provide 1 J of energy?

Q. Orbital having 3 angular nodes and 3 total nodes is

1. $5p$
2. $3d$
3. $4f$
4. $6d$

Q. The value of Planck's constant is $6.63\times {10}^{-34}js$. The velocity of light is $3.0\times {10}^{8}m{s}^{-1}$ . Which value is closest to the wavelength in nanometers of a quantum of light with frequencty of $8\times {10}^{15}{s}^{-1}$

1. 3 × 10⁷

2. 2 × 10^-25

3. 5 × 10^-8

4. 4 × 10¹

Q.

The wavelength of the radiation emitted, when a Hydrogen atom electron falls from infinity to the stationary state, would be:

Rydberg constant $=1.097\times {10}^7{\mathrm{m}}^{-1}$

1. $91\mathrm{nm}$

2. $406\mathrm{nm}$

3. $192\mathrm{nm}$

4. $9.1\times {10}^{-8}\mathrm{nm}$

Q.

Find energy of each of the photons which
(i) correspond to light of frequency 3× ${10}^{15}$ Hz.

(ii) have wavelength of 0.50 Å.

Q. The equation $E=hv$ indicates that:

1. Photons have both particle and wave nature
2. Photons are waves
3. Photons are straem of particles
4. No such inference can be drawn from the given equation

Q.

Rest mass of a photon is _______.

Q.

State the postulates of Plancks quantum theory.

Q.

An X-ray tube is operated at $1.24millionvolt$. The shortest wavelength of the produced photon will be:

1. ${10}^{-2}nm$

2. ${10}^{-3}nm$

3. ${10}^{-4}nm$

4. ${10}^{-1}nm$

Q. Calculate the energy associated with photon of light having a wavelength 6000 $\stackrel{o}{A}$. [h= $6.626\times {10}^{-27}ergs$]

1. $3.313\times {10}^{-12}erg$
2. $3.313\times {10}^{-13}erg$
3. $3.313\times {10}^{-10}erg$
4. $3.313\times {10}^{-11}erg$

Q. A wavelength of $450$ $nm$ corresponds to :
$(1$ $nm$ = ${10}^{-9}m)$

1. Frequency$\left(\nu \right)$ $=6.6\times {10}^{14}Hz$
2. Wave number$\left(\tilde{\nu }\right)$ $=2.2\times {10}^6{m}^{-1}$
3. None of the above
4. Both (a) and (b)

Q. Suppose ${10}^{-17}$J of energy is needed by the interior of the human eye to see an object, how many photons of green light $(\lambda =550nm)$ are needed to generate this minimum amount of energy?

1. 22
2. 20
3. 14
4. 28

Q. What possibly can be the ratio of the de Broglie wavelength of two electrons having the same initial energy and accelerated through $50\text{V}$ and $200\text{V}$

1. $3:5$
2. $10:3$
3. $6:2$
4. $2:1$

Q. A bulb of $40\text{W}$ is producing a light of wavelength $620\text{nm}$ with $80\%$ efficiency. Find the number of photons emitted by the bulb in $20$ seconds.
$(1\text{eV}=1.6\times {10}^{-19}\text{J},hc=12423\text{eV}\stackrel{o}{\text{A}})$

1. $2\times {10}^{19}$
2. $4\times {10}^{18}$
3. $5\times {10}^{21}$
4. $2\times {10}^{21}$

Q.

Calculate the energy in corresponding to light of wavelength $45nm.$

Q. What is quanta?

Q. In hydrogen atom, the de Broglie wavelength of an electron in the second Bohr orbit is [Given that Bohr radius, $a_0=52.9\text{pm}$]:

1. $211.6\text{pm}$
2. $211.6\pi \text{pm}$
3. $52.9\pi \text{pm}$
4. $105.8\text{pm}$

Q. Sun glasses have small amount of $AgCl$ incorporated in the lenses. When light of appropriate wavelength is exposed it turns to gray colour to reduce the glare following the reactions:
$AgCl\stackrel{hv}{\to }Ag\left(\text{Gray}\right)+\frac{1}{2}C{l}_2$

If the heat of reaction for the decomposition of $AgCl$ is $248{\text{kJ mol}}^{-1}$. Find the wavelength needed to induce the desired process?

1. $4.83\times {10}^{-7}\text{m}$
2. $9.66\times {10}^{-7}\text{m}$
3. $2.41\times {10}^{-7}\text{m}$
4. $4.83\times {10}^{-6}\text{m}$

Q.

The maximum emission wavelength at temperature $2000K$ is $4\mu m$. The maximum wavelength corresponding to temperature $2400K$ will be

Q. Calculate the wavelength of a photon having an energy of 3 eV. Take $h=6.6\times {10}^{-34}Js$

1. $4.125\times {10}^3\stackrel{\circ }{A}$
2. $5.125\times {10}^3\stackrel{\circ }{A}$
3. $7.125\times {10}^3\stackrel{\circ }{A}$
4. $4.125\times {10}^4\stackrel{\circ }{A}$

Q. A bulb emits light of wavelength $\left(\lambda \right)=4500\stackrel{o}{A}$ . The bulb is rated as $150watt$ and $8\%$ of its energy is emitted as light. If number of photons emitted is $x\times {10}^{19}$, then the value of $x$ is:
(Take $\text{planck's constant}h=6\times {10}^{-34}Js\text{and speed of light}c=3\times {10}^{8}m{s}^{-1}$)

Q. Calculate the wavelength of a photon having an energy of 2 eV

1. $6.21\times {10}^3\stackrel{\circ }{A}$
2. $6.20\times {10}^3$ nm
3. $4.41\times {10}^3$ nm
4. $4.41\times {10}^3\stackrel{\circ }{A}$

Q.

In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of 3.15 × ${10}^{–18}$ J from the radiations of 600 nm, calculate the number of photons received by the detector.

Q.

How does quantum mechanics differ from classical mechanics?

Q. A bulb emits light of $\lambda =4500\stackrel{o}{A}$. The bulb is rated as 150 watt and 8% of the energy is emitted as light. How many photons are emitted by the bulb per second?

1. $2.72\times {10}^{18}$
2. $27.2\times {10}^{18}$
3. $0.272\times {10}^{18}$
4. $2.72\times {10}^{16}$

Q.

How did plank explain the black body radiation?

Q. Iodine molecule dissociates into atoms after absorbing light of 4500 $\stackrel{o}{A}$ . If one quantum of radiation is absorbed by each molecule. Calculate the kinetic energy of iodine atoms (bond energy of $I_2=240kJmo{l}^{-1}$)

1. $0.216\times {10}^{-18}J$
2. $0.216\times {10}^{-17}J$
3. $0.216\times {10}^{-20}J$
4. $0.216\times {10}^{-19}J$

Q.

How is heat transferred by radiation?

Q. What is the ratio of the energies of two radiations in which one has a wavelength of $6000\stackrel{\circ }{A}$ the other has a wavelength of $2000\stackrel{\circ }{A}$?

1. $1:3$
2. $1:2$
3. $2:1$
4. $2:3$

Q. Calculate the wavelength of the radiation which would cause the photo-dissociation of chlorine molecule if the Cl-Cl bond energy is 243 kJ/mol.

1. $493nm$
2. $4900\mu m$
3. $4900nm$
4. $493m$