CBSE Questions for Class 12 Medical Physics Atoms Quiz 3 - MCQExams.com

If an element has 22 electrons then what will be its atomic number?
  • 10
  • 25
  • 15
  • 22
If an element X has mass number and number of proton 8 then identify element X 
  • C
  • N
  • O
  • Ar
An element necessarily have same
  • No. of protons
  • No. of electrons
  • No. of nuetrons
  • All
Smallest particle in a chemical element or compound that has the chemical properties of that element or compound is
  • Atom
  • Molecule
  • Mixture
  • Element
An element X has mass number 10, and number of neutrons =Then what will be the number of proton?
  • 10
  • 3
  • 7
  • 17
What is the mass of neutron?
  • $$1.675\times 10^{-24}g$$
  • $$9.1\times 10^{-31} kg$$
  • $$1.675\times 10^{-30}g$$
  • $$9.1\times 10^{-27}kg$$
Packets of which of the following quantity best describe photons ?
  • energy
  • mass
  • volume
  • power
  • waves
What is the electronic configuration of phosphorus?
  • 2, 8, 5
  • 2, 8, 4
  • 2, 8, 6
  • 2, 8, 3
A substance consisting of atoms which all have the same number of protons is called a/an
  • Element
  • Molecule
  • Mixture
  • Solution
$$U^{235}, U^{238}, U^{239}$$ are the atoms of the uranium. Which are called as
  • Isomers
  • Isobars
  • Isotopes
  • None of these
Which instrument was used for the discovery of the electron?
  • Plum Pudding Model
  • Oil Drop Apparatus
  • Gold Foil Experiment
  • Alpha Particle Emitter
  • Cathode Ray Tube
What is the correct order in which the listed atomic models were advanced and accepted, earliest first?
  • Bohr, planetary, plum pudding
  • Planetary, Bohr, plum pudding
  • Plum pudding, Bohr, planetary
  • Plum pudding, planetary, Bohr
  • Planetary, plum pudding, Bohr
Spectrum of sunlight is an example for
  • Band emission spectrum
  • Line absorption spectrum
  • Continuous emission spectrum
  • Continuous absorption spectrum
Which of the following can produced emission spectrum ?
  • electrons in an excited gas jump up to a higher energy level and release photons.
  • electrons in an excited gas jump down to a lower energy level and release photons.
  • electrons are released from the outer orbitals of an excited gas.
  • an unstable nucleus releases energy.
  • light is shined on a  metal surface and electrons are released.
Which of the following is NOT a postulate of Bohr's model of the hydrogen atom? 
  • Gases excited by a voltage emits a bright-light emission spectrum.
  • The position of an electron in the hydrogen atom is not defined.
  • Electron absorbs energy to make transition to a higher energy level.
  • Electron emits energy when it makes transition to a lower energy level.
  • The energy levels of the electron are quantized.
The concept of stationary orbits was proposed by.
  • J. J. Thomson
  • Rutherford
  • Neil Bohr
  • LNewton
Identify which of the following is the smallest discrete value of electromagnetic energy ?
  • photon
  • proton
  • electron
  • neutron
  • quark
Which of the following conclusions can be drawn from the Rutherford alpha scattering model?
 I. The atom is mostly empty space.
II. Electrons orbit the nucleus of the atom.
III. The atom has a dense, positively charged nucleus.
  • I only
  • II only
  • I and II only
  • II and III only
  • I, II, and III
The size of the nucleus varies as __________ power of the atomic number.
  • $$1/2$$
  • $$2$$
  • $$1/3$$
  • $$3$$
According to the quantum theory of light, the energy of light is carried in discrete units called
  • alpha particles
  • photoelectrons
  • protons
  • photons
In a laser tube, all the photons
  • have same wavelength
  • have same energy
  • move in same direction
  • move with same speed.
According to Bohr's model of hydrogen atom, relation between principal quantum number n and radius of stable orbit is 
  • $$r \propto \frac{1}{n}$$
  • $$r \propto n$$
  • $$r\propto\frac{1}{n^2}$$
  • $$r\propto n^2$$
In a cathode ray oscillograph, the focusing of beam on the screen is achieved by
  • Convex lens
  • Magnetic field
  • Electric potential
  • All of these
 When electron remains between orbits, its momentum is :
  • quantized
  • dequantized
  • emitted
  • changed always
Number of spectral lines in hydrogen atom is
  • $$8$$
  • $$6$$
  • $$15$$
  • $$\infty$$
When electron changes its orbit from outer to inner energy is :
  • absorbed
  • released
  • no change
  • remains constant
When an electron jumps from its orbit to another orbit, energy is :
  • emitted
  • absorbed
  • both absorbed and emitted
  • depends on the energy levels of the orbits
Orbits in which electrons move according to Bohr are :
  • elliptical
  • cylindrical
  • circular
  • oval
Particles having half integral spin are :
  • Electron
  • Photon
  • Proton
  • Neutron
In the discharge tube as the density of atom increases, the intensity spectral lines
  • Decreases continuously
  • Increases continuously
  • Remains constant
  • None of these
Which spectrum is continuous 
  • $$\alpha$$-rays
  • $$\beta$$-rays
  • $$\gamma$$-rays
  • All of these
Line spectrum contains information about the :
  • Atoms of the prism
  • Atoms of the source
  • Molecules of the source
  • Atoms as well as molecules of the source
In an atom an electron excites to the fourth orbit.When it jumps back to the energy level one a spectrum is formed. Total number of spectral lines in this spectrum would be
  • 3
  • 4
  • 5
  • 6
An electron jumps from $$6^{th}$$ shell in an hydrogen atom, the number of Lyman emission lines will be:
  • 5
  • 6
  • 10
  • 12
Cathode rays ___________.
  • Are the atoms moving toward the cathode
  • Are electromagnetic waves
  • Are negative ions travelling from cathode to anode
  • Are electrons emitted by cathode and travelling towards anode
When an alpha particle is emitted from a radioactive source.
  • Its atomic number increases by $$4$$
  • Its atomic number decreases by $$2$$
  • Its atomic number increases by $$2$$
  • It atomic number decreases by $$4$$
What is the wavelength of the most energetic photon emitted in the Balmer's series of the hydrogen atom?
  • $$3694 \ A$$
  • $$5756 \ A$$
  • $$3333 \ A$$
  • $$3669 \ A$$
'Electrons revolve round the nucleus in well-defined orbits, like planets revolve round the sun' was the brainchild of.
  • Arnold Sommerfeld
  • Max Born
  • Ernest Rutherford
  • Niels Bohr
Which one of the following device makes use of the electrons to strike certain substances to produce fluorescence?
  • Thermionic value
  • Photoelectric cell
  • Cathode ray oscilloscope
  • Electron gun
The number of significant figure in $$6.023 \times 10 ^ { 23 } \mathrm { mole } ^ { - 1 }$$ is
  • 4
  • 3
  • 2
  • 23
The number of orbitals in $$n=3$$ are :
  • $$1$$
  • $$4$$
  • $$9$$
  • $$16$$
To which of the following the angular velocity of the electron in the n-th Bohr orbit is proportional ? 
  • $$n^2$$
  • $$\dfrac{1}{n^2}$$
  • $$\dfrac{1}{n^{\dfrac{3}{2}}}$$
  • $$\dfrac{1}{n^3}$$
Cathode rays constitute a stream of 
  • electrons
  • protons
  • positive ions
  • negative ions.
Two photons having _________________.
  • Equal wavelengths have equal linear momenta
  • Equal energies have equal linear momenta
  • Equal frequencies have equal linear momenta
  • Equal linear momenta have equal wavelengths
The radius of a shell for $$H-atom$$ is $$4.761\,\overset{o}{A}$$. The value of n is:
  • 3
  • 9
  • 5
  • None of these
Which of the following samples will have the same number of atoms as 40 g calcium?
  • 24 g magnesium
  • 64 g silphur
  • 14 g nitrogen
  • 8 g oxygen
Cathode rays are passing through a discharge tube. In the tube, there is
  • an electric field but no magnetic field
  • a magnetic field but no electric field
  • an electric as well as a magnetic field
  • neither an electric nor a magnetic field.
The band spectra (characteristic of molecular species) is due to emission of radiation
  • Solid state
  • All of three states
  • Gaseous state
  • Liquid state
Emission spectrum of $$CO_{2}$$ gas
  • Is a line spectrum
  • Is a band spectrum
  • Is a continuous spectrum
  • Does not fall in the visible region
Consider the following two statements $$A$$ and $$B$$ and identify the correct choice in the given answers
$$A :$$ Line spectra is due to atoms in gaseous state
$$B :$$ Band spectra is due to molecules
  • Both $$A$$ and $$B$$ are false
  • $$A$$ is true and $$B$$ is false
  • $$A$$ is false and $$B$$ is true
  • Both $$A$$ and $$B$$ are true
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