11 Chemistry – 2 – Structure of Atom – Complete Chapter – Test 1 (FREE MCQ Test)
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The ground state electronic configuration of Chromium \( ( Z = 24 ) \) is:
Chromium has an exceptional configuration of \( [ Ar ] 3d^{ 5 } 4s^{ 1 } \) because half-filled subshells have extra stability.
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In vacuum, all types of electromagnetic radiation travel at the same speed, which is:
Regardless of wavelength, all electromagnetic radiations travel at the speed of light, \( 3.0 \times 10^{ 8 } m s^{ -1 } \) in a vacuum.
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In the absence of electrical or magnetic fields, cathode rays travel in:
The sources state that in the absence of an electrical or magnetic field, cathode rays travel in straight lines.
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What does the negative sign in the electronic energy expression \( E_{ n } \) for a hydrogen atom indicate?
The negative sign means the energy of the electron in the atom is lower than the energy of a free electron at rest (which is assigned zero energy).
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Which sub-atomic particle was discovered by James Chadwick in 1932 by bombarding a thin sheet of beryllium with \( \alpha \)-particles?
According to the sources, Chadwick discovered neutrons in 1932. These are electrically neutral particles with a mass slightly greater than that of protons.
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According to the \( ( n + l ) \) rule, if two orbitals have the same value of \( ( n + l ) \), which one has lower energy?
If two orbitals have the same \( ( n + l ) \) value, the one with the lower value of \( n \) has the lower energy.
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The mass number \( ( A ) \) of an atom is defined as the total number of:
The sources define the mass number as the sum of the number of protons \( ( Z ) \) and the number of neutrons \( ( n ) \).
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The radius of the first stationary state of the hydrogen atom, called the Bohr orbit, is:
The radius of the first orbit \( ( n = 1 ) \) is \( a_{ 0 } = 52.9 pm \).
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What is the currently accepted value for the electrical charge of an electron?
The sources note that while Millikan found it to be \( -1.6 \times 10^{ -19 } C \), the presently accepted value is \( -1.602176 \times 10^{ -19 } C \).
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Bohr’s model postulates that an electron can move only in those orbits where its angular momentum is an integral multiple of:
Bohr’s fourth postulate states that angular momentum \( m_{ e } vr = n h / 2\pi \) where \( n \) is an integer.
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Heisenberg’s Uncertainty Principle states that it is impossible to determine simultaneously the exact:
The principle states that the exact position and exact momentum (or velocity) of an electron cannot be determined simultaneously.
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The extra stability of half-filled and completely filled subshells is due to relatively small shielding and:
Stability is due to symmetrical distribution of electrons and maximum exchange energy.
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The series of lines in the hydrogen spectrum that appears in the visible region is known as the:
The Balmer series is the only series of lines in the hydrogen spectrum that appears in the visible region of the electromagnetic spectrum.
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Which atomic model is also commonly referred to as the “plum pudding” or “watermelon” model?
J.J. Thomson proposed that an atom is a sphere of positive charge with electrons embedded in it, similar to seeds in a watermelon.
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According to Planck’s quantum theory, the energy \( ( E ) \) of a quantum of radiation is:
Planck suggested that energy is emitted or absorbed in discrete amounts called quanta, where \( E = h\nu \).
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Atoms with the same mass number but different atomic numbers are called:
Isobars are atoms with the same mass number but different atomic numbers, such as \( ^{ 14 }{ 6 } C \) and \( ^{ 14 }{ 7 } N \).
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Who determined the ratio of electrical charge \( ( e ) \) to the mass of an electron \( ( m_{ e } ) \) using a cathode ray tube?
J.J. Thomson measured the ratio of electrical charge to the mass of an electron in 1897 by applying perpendicular electrical and magnetic fields.
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Rutherford concluded from his \( \alpha \)-particle scattering experiment that the radius of the nucleus is approximately:
Calculations by Rutherford showed that the radius of the atom is about \( 10^{ -10 } m \), while that of the nucleus is only \( 10^{ -15 } m \).
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For a given principal quantum number \( n \), the total number of orbitals is given by:
The sources confirm that for a given value of \( n \), the number of allowed orbitals is \( n^{ 2 } \).
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In the photoelectric effect, the number of electrons ejected is proportional to:
The sources state that the number of electrons ejected is proportional to the intensity or brightness of light, while their kinetic energy depends on frequency.
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Which principle states that no two electrons in an atom can have the same set of four quantum numbers?
The Pauli Exclusion Principle restricts the number of electrons in an orbital to two, and they must have opposite spins.
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According to de Broglie, the relation between wavelength \( ( \lambda ) \) and momentum \( ( p ) \) is:
de Broglie proposed that matter exhibits dual behavior and gave the relation \( \lambda = h / p = h / mv \).
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What was a major drawback of the Rutherford nuclear model regarding the motion of electrons?
According to Maxwell’s theory, accelerated charged particles (revolving electrons) should emit radiation and spiral into the nucleus, making the model unstable.
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Which quantum number determines the three-dimensional shape of the orbital?
The azimuthal quantum number \( ( l ) \), also known as the orbital angular momentum quantum number, defines the shape.
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