MDCAT Chemistry MCQs

Effusion rates depend on molar mass.
Lighter gases generally effuse faster.

Four equivalent bonding directions correspond to sp3 hybridization.
The ideal geometry is tetrahedral.

Three electron groups arrange about 120 degrees apart.
They lie in one plane.

Four electron groups point toward tetrahedral corners.
The ideal bond angle is about 109.5 degrees.

Carbon in methane has four bonding pairs and no lone pairs.
The molecular geometry is tetrahedral.

Nitrogen has three bonds and one lone pair.
The lone pair changes the molecular shape from tetrahedral electron geometry.

Oxygen has two bonding pairs and two lone pairs.
Lone-pair repulsion produces a bent molecule.

Carbon has two electron domains from the two double bonds.
They arrange 180 degrees apart.

Boron has three bonding regions and no lone pairs.
The molecule is planar with approximately 120-degree angles.

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

Alkali metals have one valence electron.
They commonly form +1 ions and are highly reactive.

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