Pakistan MCQs

Excited atoms can return to lower levels by emitting energy.
Atomic spectra arise from these transitions.

Covalent bonds commonly form between nonmetal atoms.
Shared electrons are attracted to both nuclei.

First ionization energy removes the first electron from a neutral gaseous atom.
Successive ionization energies remove additional electrons.

Metallic bonding explains conductivity and malleability.
Valence electrons move through the metal lattice.

Electron affinity reflects attraction for an added electron.
Its sign and magnitude vary across the periodic table.

Bond polarity arises from electronegativity differences.
The more electronegative atom gains partial negative charge.

Electronegativity helps predict bond polarity.
Fluorine has the highest common electronegativity.

Identical atoms form nonpolar covalent bonds.
Small electronegativity differences also give nearly nonpolar bonds.

Valence electrons largely determine chemical reactivity.
Elements in a group often share similar valence configurations.

Thomson's cathode-ray experiments revealed negatively charged particles.
He proposed an early model with electrons in positive matter.

Periodic trends arise from repeating valence-shell patterns.
The periodic table organizes these regularities.

Atomic number identifies the element.
In a neutral atom it also equals the number of electrons.