CBSE Questions for Class 9 Chemistry Structure Of The Atom Quiz 12 - MCQExams.com

Rutherford's experiment, which established the nuclear model of the atom, used a beam of:
  • $$\beta$$-particles, which impinged on a metal foil and got absorbed
  • $$\gamma$$-rays, which impinged on a metal foil and ejected electrons
  • helium atoms, which impinged on a metal foil and got scattered
  • helium nuclei, which impinged on a metal foil and got scattered
The radius of nucleus is:
  • proportional to its mass number
  • inversely proportional to its mass number
  • proportional to the cube root of its mass number
  • not related to its mass number
The introduction of a neutron into the nuclear composition of an atom would lead to a change in:
  • its atomic mass
  • its atomic number
  • the chemical nature of the atom
  • number of the electron also
Rutherford's experiment established that:
  • inside the atom there is a heavy positive centre
  • nucleus contains protons and neutrons
  • most of the space in an atom is empty
  • size of nucleus is very small
In the Bohr's model of the atom:
  • the radius of $$n$$th orbit is proportional to $${ n }^{ 2 }$$
  • the total energy of the electron in the $$n$$th orbit is inversely proportional to '$$n$$'
  • the angular momentum of the electron is integral multiple of $${ h }/{ 2\pi }$$
  • the magnitude of potential energy of an electron in an orbit is greater than kinetic energy
In a hydrogen like sample electron is in 2nd excited state,the energy of the 4th state of this sample is -13.6 eV,then the incorrect statement is:
  • Atomic number of element is 4.
  • 3 different types of spectral lines will be observed if electrons make transition upto ground state from the 2nd excited state.
  • A 25 eV photon can set free the electron from the 2nd excited state of this sample
  • 2nd line of Balmer series of this sample has same energy value as 1st excitation energy of H-atom
The nucleus of an atom was discovered due to the experiment carried out by:
  • Bohr
  • Rutherford
  • Moseley
  • Thomson
Which of the following observations was not correct during Rutherford's scattering experiment?
  • Most of the $$\alpha$$-particles passed through the gold foil undeflected.
  • A small fraction of the $$\alpha$$-particles was deflected by small angles.
  • A large number of the $$\alpha$$-particles were bounced back.
  • A very few $$\alpha$$-particles (~1 in 12,000) were bounced back.
The Ionisation potential of Hydrogen is $$2.17\times 10^{-11}erg/ atom$$. The energy of the electron in the second orbit of the hydrogen atom is?
  • $$-\dfrac {2.17\times 10^{-11}}{2}$$
  • $$-\dfrac {2.17\times 10^{-11}}{2^{2}}$$
  • $$-\dfrac {2.17\times 10^{-7}}{2^{2}}$$
  • $$-\dfrac {2.17\times 10^{11}}{2^{2}}$$
Which of the following conclusions regarding the structure of the atom is based on Rutherford's $$\alpha$$-particle scattering experiment?
  • The positive charge is concentrated in a very small volume of the atom.
  • The positive charge is scattered with the electrons throughout the atom.
  • The volume occupied by the nucleus is half of the volume of atom.
  • Most of the space in the atom is occupied by the neutrons.
The density of nucleus is of the order of:
  • $${ 10 }^{ 5 }kg{ m }^{ -3 }$$
  • $${ 10 }^{ 10 }kg{ m }^{ -3 }$$
  • $${ 10 }^{ 17 }kg{ m }^{ -3 }$$
  • $${ 10 }^{ 25 }kg{ m }^{ -3 }$$
Which of the following properties of atom could be explained correctly by Thomson's model of atom?
  • Overall neutrality of atom
  • Spectra of hydrogen atom
  • Position of electrons, protons and neutrons in atom
  • Stability of atom
In Bohr series of lines of hydrogen spectrum, the third line from the red corresponds to which one of the following inter-orbit jumps of the electron for Bohr orbits in an atom of hydrogen?
  • $$2\rightarrow 5$$
  • $$3\rightarrow 2$$
  • $$5\rightarrow 2$$
  • $$4\rightarrow 1$$
Which of the following conclusions could not be derived from Rutherford's $$\alpha$$-particles scattering experiment?
  • Most of the space in the atom is empty.
  • The radius of the nucleus is about $$10^5$$ times less than the radius of the atom.
  • Electrons move in a circular path of fixed energy called orbits.
  • Electrons and the nucleus are held together by the electrostatic force of attraction.
In a Bohr's model of an atom when an electron jumps from n=1 to n=3, how much energy will be emitted or absorbed in erg?
  •  $$2.15\times { 10 }^{ -11 }$$
  • $$0.191\times { 10 }^{ -10 }$$
  • $$2.389\times { 10 }^{ -12 }$$
  • $$0.239\times { 10 }^{ -10 }$$
Radius of $$2nd$$ shell of $$He^+$$ (where $$a_0$$- Bohr radius)
  • $$3a_0$$
  • $$a_0$$
  • $$\dfrac{3}{2}a_0$$
  • $$2a_0$$
Atomic radius is of the order of $$10^{-8}\ cm$$ and nuclear radius is of the order of $$10^{-13}\ cm$$. The fraction of atom occupied by nucleus is:
  • $$10^{-5}$$
  • $$10^{5}$$
  • $$10^{-15}$$
  • none of these
How many sub-atomic particles are present in an $$\alpha $$- particle used in Rutherford's scattering experiment?
  • Protons - 4, Neutrons - 0, Electrons - 0
  • Protons - 2, Neutrons - 0, Electron - 2
  • Protons - 2, Neutron - 2, Electron - 0
  • Protons - 2, Neutron - 2, Electron - 1
An atom can be smashed and broken into many nuclear particles by the high acceleration (increasing speed) imparted in:
  • a chromatograph
  • a cyclotron
  • an electron microscope
  • acathode-ray tube
What is the ratio of time periods $$(\dfrac{T_1}{T_2})$$ in $$2^{nd}$$ orbit of hydrogen atom to third orbit of $$He^+$$ ion?
  • $$\dfrac{8}{27}$$
  • $$\dfrac{32}{27}$$
  • $$\dfrac{27}{32}$$
  • $$\dfrac{27}{8}$$
A single electron orbits a stationary nucleus of charge $$+Z$$, where $$Z$$ is a constant. It requires 47.2 eV to excite electron from second Bohr orbit to third Bohr orbit, find the value of $$Z$$.
  • 1
  • 3
  • 5
  • 4
The nucleus of the atom $$\left( Z>1 \right) $$ consists of:
  • Proton and neutron
  • Proton and electron
  • Neutron and electron
  • Proton, neutron and electrons
The radius of the hydrogen atom in the ground state is $$0.53 {\mathring A}$$, the radius of $$L{i^{2 + }}$$ in a similar state is____.
  • $$1.06 {\mathring A}$$
  • $$0.265 {\mathring A}$$
  • $$0.175 {\mathring A}$$
  • $$0.53 {\mathring A}$$
Ionization energy of $${He}^{+}$$ is $$19.6\times {10}^{-18}J{atom}^{-1}$$. The energy of the first stationary state ($$n=1$$) of $${Li}^{2+}$$ is
  • $$4.41\times {10}^{-16}J{atom}^{-1}$$
  • $$-4.41\times {10}^{-17}J{atom}^{-1}$$
  • $$-2.2\times {10}^{-15}J{atom}^{-1}$$
  • $$-8.82\times {10}^{-17}J{atom}^{-1}$$
Energy of the third orbit of Bohr's atom is:
  • $$-13.6$$ eV
  • $$-3.4$$ eV
  • $$-1.5$$ eV
  • none of these
Which of the following statements is incorrect regarding Rutherford's model of atom?
  • The electrons revolve around the nucleus in fixed energy orbits
  • It is a stable model of atom which resembles our solar sysytem
  • The distribution of electrons in the orbits was given by Rutherford
  • It could not explain the atomic spectra of hydrogen
The radius of $$He^+$$ ion is $$x\ \mathring{A}$$  in its ground state. The radius of $$Li^{2+}$$ ion in the ground state ($$ \mathring{A}$$ ) is:
  • $$\dfrac{2x}{3}$$
  • $$\dfrac{3x}{2}$$
  • $$\dfrac{2}{3x}$$
  • $$\dfrac{3}{2x}$$
Which one of the following is considered as the main postulate of Bohr's model of atom
  • Protons are present in the nucleus
  • Electrons are revolving around the nucleus
  • Centrifugal force produced due to the revolving electrons balances the force of attraction between electron and protons
  • Angular momentum of electron is an integral multiple of $$\dfrac{h}{2\pi}$$
Bohr's theory can be applied to determine the?
  • electron gain enthalpy of hydrogen atom
  • Electronegativity of $${ Li }^{ 2+ }$$ ion
  • second ionization energy of helium atom
  • first ionization energy of Be atom
The ratio of the energy of the electron in the ground state of hydrogen to the electron in first excited state of $$Be^{3+}$$ is 
  • $$1 : 4$$
  • $$1 : 8$$
  • $$1 : 16$$
  • $$16 : 1$$
0:0:1


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