ECAT MCQs

Aluminum is the most abundant crustal metal.
It is commonly found in aluminosilicate minerals and bauxite.

Alkali metals have one valence electron.
They usually lose it to form +1 ions.

Group 2 metals have two valence electrons.
They commonly lose both and form +2 ions.

Filled valence shells are especially stable.
Noble gases therefore have little tendency to gain or lose electrons.

Fluorine has very high electronegativity and a weak F-F bond.
It is the strongest elemental oxidizing halogen.

Allotropes differ in atomic arrangement and properties.
Diamond and graphite are carbon allotropes.

PH=-log(1×10^-3).
The result is 3.

Graphite has delocalized electrons within its layers.
These electrons allow electrical conduction.

POH=-log(1×10^-4).
The result is 4.

Every carbon is tetrahedrally bonded to four others.
The extended network resists deformation.

Higher temperature increases collision frequency and energetic collisions.
More particles exceed the activation-energy barrier.

More particles per volume collide more often.
The exact effect is described by the rate law.