The smallest particle of an element that retains its identity is: A) Molecule B) Atom C) Ion D) Electron Answer: B) Atom
Who discovered the electron? A) Rutherford B) Dalton C) J.J. Thomson D) Bohr Answer: C) J.J. Thomson
The charge on an electron is: A) Positive B) Neutral C) Negative D) Variable Answer: C) Negative
The nucleus of an atom contains: A) Electrons only B) Protons and neutrons C) Neutrons only D) Protons only Answer: B) Protons and neutrons
Atomic number represents the number of: A) Neutrons B) Electrons C) Protons D) Nucleons Answer: C) Protons
Mass number is the sum of: A) Electrons + Protons B) Protons + Neutrons C) Neutrons + Electrons D) Protons only Answer: B) Protons + Neutrons
The model of atom proposed by Rutherford is: A) Plum pudding model B) Nuclear model C) Planetary model D) Quantum model Answer: B) Nuclear model
Which particle has no charge? A) Proton B) Electron C) Neutron D) Positron Answer: C) Neutron
The size of an atom is determined by: A) Nucleus B) Electron cloud C) Protons D) Neutrons Answer: B) Electron cloud
Bohr’s model is applicable to: A) All atoms B) Hydrogen atom C) Heavy atoms D) Molecules Answer: B) Hydrogen atom
The maximum number of electrons in K shell is: A) 2 B) 8 C) 18 D) 32 Answer: A) 2
The maximum electrons in a shell is given by: A) n² B) 2n C) 2n² D) n³ Answer: C) 2n²
The principal quantum number is represented by: A) l B) n C) m D) s Answer: B) n
The shape of orbital is determined by: A) n B) l C) m D) s Answer: B) l
The s-orbital has shape: A) Dumbbell B) Spherical C) Elliptical D) Linear Answer: B) Spherical
The p-orbital has shape: A) Spherical B) Dumbbell C) Circular D) Irregular Answer: B) Dumbbell
The number of orbitals in p-subshell is: A) 1 B) 2 C) 3 D) 5 Answer: C) 3
Maximum electrons in p-subshell: A) 2 B) 4 C) 6 D) 8 Answer: C) 6
Pauli Exclusion Principle states: A) Electrons fill lowest energy first B) No two electrons have same set of quantum numbers C) Orbitals fill singly first D) Energy is quantized Answer: B) No two electrons have same set of quantum numbers
Hund’s Rule deals with: A) Spin B) Orbital shape C) Electron pairing D) Energy levels Answer: C) Electron pairing
Aufbau principle means: A) Electrons fill randomly B) Electrons fill higher energy first C) Electrons fill lower energy first D) No fixed order Answer: C) Electrons fill lower energy first
Isotopes have same: A) Mass number B) Atomic number C) Neutrons D) Mass Answer: B) Atomic number
Isobars have same: A) Atomic number B) Mass number C) Electrons D) Protons Answer: B) Mass number
Isoelectronic species have same: A) Protons B) Electrons C) Neutrons D) Mass Answer: B) Electrons
Energy of electron depends on: A) Shell B) Spin C) Proton D) Charge Answer: A) Shell
The orbital where probability is highest is: A) Nucleus B) Shell C) Orbital D) Subshell Answer: C) Orbital
Angular momentum is quantized in: A) Thomson model B) Rutherford model C) Bohr model D) Dalton model Answer: C) Bohr model
The charge of proton is: A) Negative B) Positive C) Neutral D) Zero Answer: B) Positive
Atomic mass unit is: A) 1/16 of oxygen B) 1/12 of carbon-12 C) 1/10 of hydrogen D) 1/14 of nitrogen Answer: B) 1/12 of carbon-12
Which is heavier? A) Electron B) Proton C) Neutron D) Same Answer: C) Neutron
The number of subshells in n=3: A) 1 B) 2 C) 3 D) 4 Answer: C) 3
Number of orbitals in d-subshell: A) 3 B) 5 C) 7 D) 9 Answer: B) 5
Maximum electrons in d-subshell: A) 6 B) 8 C) 10 D) 12 Answer: C) 10
f-subshell has orbitals: A) 5 B) 7 C) 9 D) 11 Answer: B) 7
Maximum electrons in f-subshell: A) 10 B) 12 C) 14 D) 16 Answer: C) 14
Spin quantum number values are: A) 0,1 B) +½, -½ C) 1,2 D) -1,0 Answer: B) +½, -½
Magnetic quantum number determines: A) Size B) Shape C) Orientation D) Energy Answer: C) Orientation
Principal quantum number determines: A) Shape B) Size C) Orientation D) Spin Answer: B) Size
Subshell is defined by: A) n B) l C) m D) s Answer: B) l
Maximum orbitals in shell n=2: A) 2 B) 4 C) 6 D) 8 Answer: B) 4
Total electrons in n=2 shell: A) 2 B) 4 C) 6 D) 8 Answer: D) 8
The region of space with high electron probability is: A) Shell B) Orbital C) Nucleus D) Subshell Answer: B) Orbital
Quantum theory was proposed by: A) Bohr B) Planck C) Rutherford D) Dalton Answer: B) Planck
Energy is emitted in form of: A) Waves B) Photons C) Electrons D) Protons Answer: B) Photons
The energy of photon is: A) hv B) mc² C) mv² D) h/m Answer: A) hv
Frequency is denoted by: A) c B) v C) λ D) h Answer: B) v
Speed of light is: A) 3×10⁶ m/s B) 3×10⁸ m/s C) 3×10¹⁰ m/s D) 3×10⁴ m/s Answer: B) 3×10⁸ m/s
Relation between frequency and wavelength: A) v = cλ B) c = vλ C) λ = v/c D) v = λ/c Answer: B) c = vλ
Electron transition releases: A) Proton B) Photon C) Neutron D) Ion Answer: B) Photon
Ground state means: A) Highest energy B) Lowest energy C) Excited state D) Ionized state Answer: B) Lowest energy
Excited state of atom means: A) Lowest energy B) Highest energy C) Electron in higher energy level D) No electrons Answer: C) Electron in higher energy level
Emission spectrum is produced when: A) Electron absorbs energy B) Electron falls to lower level C) Proton moves D) Neutron decays Answer: B) Electron falls to lower level
Absorption spectrum occurs when: A) Electron emits energy B) Electron gains energy C) Proton loses energy D) Nucleus splits Answer: B) Electron gains energy
Number of orbitals in n=4 shell: A) 4 B) 8 C) 16 D) 32 Answer: C) 16
Maximum electrons in n=4 shell: A) 16 B) 24 C) 32 D) 64 Answer: C) 32
Heisenberg Uncertainty Principle states: A) Exact position known B) Exact momentum known C) Both position and momentum cannot be known simultaneously D) Energy constant Answer: C) Both position and momentum cannot be known simultaneously
Wave nature of electron was proposed by: A) Bohr B) de Broglie C) Rutherford D) Dalton Answer: B) de Broglie
de Broglie wavelength is given by: A) λ = h/mv B) λ = mv/h C) λ = hmv D) λ = v/h Answer: A) λ = h/mv
Quantum mechanical model is based on: A) Classical theory B) Probability C) Fixed paths D) Newton laws Answer: B) Probability
Orbital is: A) Path B) Region of probability C) Shell D) Energy level Answer: B) Region of probability
Electron cloud represents: A) Nucleus B) Electron density C) Proton area D) Neutron space Answer: B) Electron density
The first shell is also called: A) L B) M C) K D) N Answer: C) K
L shell corresponds to: A) n=1 B) n=2 C) n=3 D) n=4 Answer: B) n=2
Energy levels are also called: A) Orbitals B) Shells C) Subshells D) Nucleus Answer: B) Shells
Subshells are denoted by: A) Numbers B) Letters C) Symbols D) Codes Answer: B) Letters
Sequence of subshell filling follows: A) Increasing mass B) Increasing energy C) Decreasing energy D) Random Answer: B) Increasing energy
1s orbital has electrons: A) 1 B) 2 C) 3 D) 4 Answer: B) 2
Electron configuration of Hydrogen: A) 1s² B) 1s¹ C) 2s¹ D) 2p¹ Answer: B) 1s¹
Atomic number of hydrogen: A) 2 B) 1 C) 3 D) 4 Answer: B) 1
Number of neutrons = A) Atomic number – mass number B) Mass number – atomic number C) Protons + electrons D) Protons only Answer: B) Mass number – atomic number
Charge of neutron: A) +1 B) -1 C) 0 D) +2 Answer: C) 0
Cathode rays consist of: A) Protons B) Electrons C) Neutrons D) Ions Answer: B) Electrons
Canal rays are: A) Electrons B) Protons C) Neutrons D) Photons Answer: B) Protons
Rutherford experiment used: A) Alpha particles B) Beta particles C) Gamma rays D) Electrons Answer: A) Alpha particles
Most of the atom is: A) Solid B) Empty space C) Liquid D) Gas Answer: B) Empty space
Nucleus is: A) Large B) Small and dense C) Neutral D) Empty Answer: B) Small and dense
Atomic radius depends on: A) Nucleus B) Electron distribution C) Neutrons D) Mass Answer: B) Electron distribution
Ion is formed by: A) Losing/gaining electrons B) Losing protons C) Losing neutrons D) Splitting nucleus Answer: A) Losing/gaining electrons
Cation is: A) Negative ion B) Positive ion C) Neutral atom D) Molecule Answer: B) Positive ion
Anion is: A) Positive ion B) Negative ion C) Neutral D) Proton Answer: B) Negative ion
Atomic spectrum is: A) Continuous B) Line spectrum C) Band spectrum D) Mixed Answer: B) Line spectrum
Quantum number ‘l’ ranges from: A) 0 to n B) 0 to n-1 C) 1 to n D) 1 to n-1 Answer: B) 0 to n-1
Value of l for s-orbital: A) 1 B) 0 C) 2 D) 3 Answer: B) 0
Value of l for p-orbital: A) 0 B) 1 C) 2 D) 3 Answer: B) 1
Maximum value of m is: A) +l B) -l C) ±l D) 0 Answer: C) ±l
Total orbitals in a shell = A) n² B) 2n² C) n D) 2n Answer: A) n²
Electron spin explains: A) Charge B) Magnetic property C) Mass D) Size Answer: B) Magnetic property
Bohr radius refers to: A) Nuclear size B) Electron orbit radius C) Proton size D) Neutron size Answer: B) Electron orbit radius
The energy of orbit increases with: A) n decreases B) n increases C) mass increases D) charge decreases Answer: B) n increases
Ground state hydrogen has energy: A) Maximum B) Minimum C) Zero D) Infinite Answer: B) Minimum
Transition from higher to lower level emits: A) Electron B) Photon C) Proton D) Ion Answer: B) Photon
Transition from lower to higher level requires: A) Emission B) Absorption C) Neutralization D) Ionization Answer: B) Absorption
The spectral lines are: A) Continuous B) Discrete C) Random D) Mixed Answer: B) Discrete
Orbit and orbital differ in: A) Shape B) Concept C) Energy D) Size Answer: B) Concept
Orbital can hold maximum: A) 1 electron B) 2 electrons C) 3 electrons D) 4 electrons Answer: B) 2 electrons
Electron configuration follows: A) Random order B) Aufbau principle C) Only Pauli principle D) Only Hund rule Answer: B) Aufbau principle
Degenerate orbitals have: A) Same shape B) Same energy C) Same size D) Same spin Answer: B) Same energy
Which subshell fills after 3p? A) 4s B) 3d C) 4p D) 2d Answer: A) 4s
Which has lowest energy? A) 2p B) 3s C) 2s D) 3p Answer: C) 2s
Modern atomic theory is based on: A) Classical physics B) Quantum mechanics C) Dalton theory D) Rutherford theory Answer: B) Quantum mechanics
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