Test: Spectrum

15 Questions MCQ Test Chemistry Class 11 | Test: Spectrum

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For Balmer series,the initial state n1 is :


The Balmer series just sets n1 = 2, which means the value of the principal quantum number (n) is two for the transitions being considered. Balmer’s formula can therefore be written:

1/λ = RH ((1/22) − (1 / n22))


Calculate the wavelength of light that corresponds to the radiation that is given off during the transition of an electron from the n = 5 to n = 2 state of the hydrogen atom.


1/wavelength =RH x z2 x (1/22-1/52) =109677 x 1 x (1/4-1/25) =109677 x 21/100 =2303.2m wavelength=1/2303.2m =1/2303.2 x 107nm =434.1nm~434nm


 Which of the following subatomic particles is responsible for the spectrum of radiation emitted by an element or compound?


Any radiation is emitted in the quantized form as photons. These photons are actually generated when an electron changes its energy level. This can happen if the atom gets the required work function. For e.g. The emission of X Ray. When the cathode ray hits the nuclei of heavier metals, two cases may occur - 
1)Nuclei absorbs the electron from K shell and this process results in radiation of energy in form of X Ray photons. 
2)Auger Effect: Sometimes during the collision, an electron from main atom can also be emitted, releasing energy in form of X Ray photons. So, Now it should be more clear that while photons are the product, the real culprit behind the crime scene. So correct option is B These things can be understood easily if you know the basics of Particle Physics.


The total energy of an electron in the nth orbit of a hydrogen atom is given by the formula En = -13.6 eV/n2. What does the negative energy for an electron indicate?


The negative sign means that the energy of the electron in the atom is lower than the energy of a free electron at rest. A free electron at rest is an electron that is infinitely far away from the nucleus and is assigned the energy value zero.


Which of the following is not true about Bohr’s model of the atom?


It was De broglie who proposed the dual nature of matter and that of electrons. Davisson and germer went on to experimentally verify his theory, regarding nature of electrons(they have both particle and wave nature).
Heisenberg further introduced the uncertainty principle, related to dual nature of matter.
Bohr never putforth any such ideals and considered electron as a particle.


 In the absorption spectrum, the wavelengths which are absorbed, are missing and they appear as:


Light not absorbed by the sample will, as before, be separated (dispersed) into its component wavelengths (colors) by the prism. The appearance of the spectrum will resemble that obtained without the sample in place, with the exception that those wavelengths which have been absorbed are missing, and will appear as dark lines within the spectrum of colors. If a piece of the photographic film is used instead of the card, the absorption spectrum can be recorded.


Many home bathrooms have infrared light fixtures to help warm the room, and this light is not cancer causing. Which of the following quality make it so useful?


An infrared heat lamp is a lamp that uses a special form of incandescent light bulb primarily for the purposes of heat production rather than to generate light. These lamps do produce some light, but most of the energy that they consume is directed towards heating the room.

The incandescent bulb or bulbs in the lamp produce heat by generating infrared light. Normal light bulbs are designed to produce light and the heat they generate is considered to be waste. Conversely, the light bulbs that are used in heat lamps are intended primarily to produce heat, with the light being essentially a waste product.


By use of a suitable filter, the green mercury emission line can be isolated. This line has a wavelength of 546.1 nm. What is the frequency? [1 Hz = 1 s-1]


using the formula:


 An electron falls from one energy level to another; it releases a certain amount of light with a frequency of 5.100 x 1014 Hz. What energy is associated with this electron?


E = h.v

= 6.63 x 10-34 x 5.1 x 1014

= 33.8 x 10-20 J


The energy associated with the transition of an electron from the n=1 state to the n=3 state of H atoms is:


The formula to calculate the excitation energy is 13.6Z2(1/n12-1/n22), but this gives value in eV. To convert it in Joules we divide it by 6.24×1018 Here, Z=1,n1=1,n2=3 Putting these values in above formula we have, [13.6×1(1-1/9)]/6.24×1018 =(13.6×8×10-18)/(9×6.24) =1.94×10-18 Hence, the correct answer is C.


For Paschen series, the initial state n1 is :


Paschen series from n = 4, 5, 6, 7……to n = 3


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


The Zeeman effect is the splitting of the spectral lines of an atom in the presence of a strong magnetic field. The effect is due to the distortion of the electron orbitals because of the magnetic field. The (normal) Zeeman effect can be understood classically, as Lorentz predicted. 


EM spectrum shows all forms of radiation except one of the followings:


Beta radiation is used for tracers and monitoring the thickness of materials.

Doctors may use radioactive chemicals called tracers for medical imaging. Certain chemicals concentrate in different damaged or diseased parts of the body, and the radiation concentrates with it. Radiation detectors placed outside the body detect the radiation emitted and, with the aid of computers, build up an image of the inside of the body.

Radiation is used in industry in detectors that monitor and control the thickness of materials such as paper, plastic and aluminium. The thicker the material, the more radiation is absorbed and the less radiation reaches the detector. It then sends signals to the equipment that adjusts the thickness of the material.


Which of the following is not a type of electromagnetic radiation?


The groups of electromagnetic radiation are radio waves, microwaves, infrared waves, visible lightwaves, ultraviolet waves, x-ray waves, and gammawaves. I have listed those seven types of electromagnetic radiation in increasing energy.Sound wave energy is distinctly different than electromagnetic wave energy.


 How much energy is needed to ionize a hydrogen atom if electron is present in n=1 orbit?


For hydrogen Z=1,
and n is given as 1,
E= -13.6 × n power 2/ Z.
E= - 13.6 × 1 power 2/ 1.
E= -13.6e.v.

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