Which experiment proved that the speed of light is constant in all frames of reference?
a) James Clerk Maxwell
b) Michelson and Morley
c) Miller and Stanley
d) Werner Heisenberg
Answer: b
The photoelectric effect refers to the emission of electrons when:
a) A metal is heated
b) A strong electric field is applied
c) Electrons strike the surface
d) Light of appropriate wavelength shines on the metal
Answer: d
What is the Bohr radius of a hydrogen atom?
a) 0.529 × 10⁻⁷ cm
b) 0.529 × 10⁻⁸ cm
c) 0.529 × 10⁻⁹ cm
d) 0.529 × 10⁻¹⁰ cm
Answer: d
Atoms with the same number of protons but different numbers of neutrons are called:
a) Isotopes
b) Cations
c) Higgs bosons
d) Anions
Answer: a
How many unpaired electrons are there in Mn²⁺?
a) 1
b) 3
c) 4
d) 5
Answer: d
What is the value of Planck’s constant?
a) 6.62 × 10⁻³⁴ J
b) 6.62 × 10⁻³⁴ J·s
c) 6.62 × 10⁻³⁴ erg·s
d) None of the above
Answer: b
The reverse process of X-ray emission is known as:
a) Raman effect
b) Compton effect
c) Zeeman effect
d) Photoelectric effect
Answer: d
Isobars are lines on a weather map representing equal:
a) Humidity
b) Temperature
c) Rainfall
d) Atmospheric pressure
Answer: d
Which atom has a non-spherical outermost orbital?
a) Hydrogen
b) Lithium
c) Beryllium
d) Boron
Answer: d
Who first explained the hydrogen spectrum?
a) Dalton
b) Niels Bohr
c) Rutherford
d) J.J. Thomson
Answer: b
In which of the following pairs are the ions/atoms isoelectronic?
Na⁺ and Ne
Na⁺ and K⁺
K⁺ and Cl⁻
a) 1, 2 and 3
b) 1 and 2
c) 2 and 3
d) 1 and 3
Answer: d
Bohr’s concept of atomic orbitals was contradicted by:
a) De Broglie’s hypothesis
b) Heisenberg’s uncertainty principle
c) Planck’s quantum theory
d) Hund’s rule
Answer: b
The spectrum of helium is most similar to the spectrum of:
a) Hydrogen
b) Sodium
c) He⁺
d) Li⁺
Answer: d
Which of the following waves can travel through a vacuum?
Radio waves
Light waves
X-rays
Ultrasonic waves
a) 1, 2 and 3
b) 1, 2, 3 and 4
c) 2, 3 and 4
d) 1 and 4
Answer: a
Atoms of the same element with different mass numbers are called:
a) Isobars
b) Isotopes
c) Isotones
d) Isomers
Answer: b
“No two electrons in an atom can have the same set of all four quantum numbers.” This is known as:
a) Hund’s rule
b) Pauli’s exclusion principle
c) Heisenberg’s uncertainty principle
d) Avogadro’s law
Answer: b
In the Lyman series, electrons fall to which energy level?
a) K-shell (n = 1)
b) M-shell (n = 3)
c) N-shell (n = 4)
d) L-shell (n = 2)
Answer: a
The chemical properties of isotopes are:
a) Always the same
b) Always different
c) Not necessarily the same
d) Not necessarily different
Answer: a
The principle stating that each orbital is singly occupied before any pairing occurs is:
a) Einstein’s theory
b) Rutherford’s hypothesis
c) Pauli’s exclusion principle
d) Hund’s rule
Answer: d
If an electron and a photon have the same wavelength, they also share the same:
a) Velocity
b) Linear momentum
c) Angular momentum
d) Energy
Answer: b
Isobars are atoms that have:
a) Same mass numbers, different atomic numbers
b) Different mass numbers, same atomic numbers
c) Same mass and atomic numbers
d) Different mass and atomic numbers
Answer: a
Mercury and sodium street lights glow because of:
a) Atomic absorption
b) Electron absorption
c) Atomic emission
d) Electron emission
Answer: c
The alpha particle (α-particle) carries two positive charges and its mass is nearly equal to that of:
a) Two protons
b) A helium atom
c) Two positrons and two neutrons combined
d) Two positrons
Answer: b