Pakistan MCQs

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

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

After formation, a coordinate bond behaves like an ordinary covalent bond.
The electron-pair donor provides both bonding electrons.

The octet rule is a useful main-group bonding guideline.
Hydrogen, boron, and expanded-valence species are exceptions.

Lewis structures use lines and dots for bonds and lone pairs.
They help predict connectivity and formal charge.

Quantum mechanics describes electron probability distributions.
An orbital can hold up to two electrons with opposite spins.

Halogens have seven valence electrons.
They commonly form -1 ions.

The Pauli exclusion principle allows two electrons per orbital.
They must have opposite spin quantum numbers.

An s subshell contains one orbital.
It can hold a maximum of two electrons.

A p subshell contains three orbitals.
It can hold a maximum of six electrons.

A d subshell contains five orbitals.
At two electrons per orbital, it holds ten electrons.

The Aufbau principle guides ground-state configurations.
Actual filling order follows orbital energies.