Atoms Test

Result

Atoms Test - 5

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Weekly Quiz Competition

Question 1
1 / -0

Fluorescence is

A
a form of luminescence occuring when an excited atom relaxes to its ground state.

B
light coming out from a bulb or candle.

C
a form of luminescence occuring when an atom in its ground state is excited.

D
a form of luminescence occuring when an atom in its ground state goes into stable excited states.

Solution

Fluorescence occurs when a molecule, atom or nanostructure after being excited to a higher quantum state, by some type of energy (light or electromagnetic radiation), relaxes to its ground state by emitting a photon of light. The emitted light has longer wavelength (lower energy) than absorbed radiation.
Question 2
1 / -0

Reason why there are many lines in an atomic spectrum is because

A
There are many atoms in different states of excitation making transition to different states

B
There are many atoms in different states of excitation making transition to the same state

C
All atoms are in the same excited state and make transition to same state

D
All atoms are in the same excited state and make transition to different states

Solution

Electromagnetic radiation is emitted when an excited atom makes a transition from higher energy state to a lower energy state. There are many electron transition for each atom and each atom has specific energy difference leading to different radiated wavelength.
Question 3
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Fluorescent lamps are more efficient than incandescent lamps in converting electrical energy to visible light because

A
they do not waste as much energy producing (invisible) infrared photons

B
they do not use uv radiations

C
they produce more white light

D
they do not waste as much energy producing visible photons

Solution

A fluorescent lamp converts electrical energy to useful light much more efficiently than incandescent lamps. Incandescent bulbs convert only less than 5% of the energy they use into visible light.
Question 4
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According to Bohr model radiation takes place when

A
there is transition from one of the unstable orbits of definite energy to another of higher energy

B
there is transition from one of the stable orbits of definite energy to another of higher energy

C
there is transition from one of the unstable orbits of definite energy to another of same energy

D
there is transition from one of the stable orbits of definite energy to another of lower energy

Solution

An electron radiates energy when it jumps from a higher energy (stable, non-radiating) orbit to a lower energy orbit. There is emissin of a photon during this process and the frequency of the photon emitted is given by hv = E_t - E_f where E_t and E_f are energies of the intial and final states, and E_t > E_f.
Question 5
1 / -0

According to Bohr model allowed values of angular momentum are

A
integral multiples of h/ π

B
integral multiples of h/2π

C
integral multiples of h

D
continuous

Solution

Out of several number of orbits an electron can revolve only in those orbits in which angular momentum is integral multiple of h/2π. Angular momentum of the n^th orbit electron is L = nh/2π