MDCAT Chemistry MCQs

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

Lone pairs influence shape and reactivity.
They repel bonding pairs strongly in VSEPR theory.

Noble gases have filled valence shells in their common ground states.
They are generally unreactive.

A single bond has order one, double bond two, and triple bond three.
Higher bond order generally means shorter, stronger bonds.

Increasing nuclear charge pulls electrons closer within the same main shell.
Effective nuclear attraction generally increases across a period.

Triple bonds have higher bond order than single or double bonds.
They are usually shorter and stronger.

Additional electron shells are added down a group.
This outweighs the increased nuclear charge.

No single resonance structure fully represents the electron distribution.
The real structure is a resonance hybrid.

Effective nuclear charge generally increases across a period.
Electrons are therefore harder to remove, with some exceptions.

Formal charge helps compare possible Lewis structures.
Preferred structures often minimize charge separation.

Valence electrons are farther from the nucleus and more shielded down a group.
They are generally easier to remove.

Electron groups arrange to minimize repulsion.
Lone pairs and bonding regions determine molecular geometry.