Unit 3 B Practice Exam

Two molecules of HBr collide and then for  $H_2$   and  $Br_2$  During the collision, the bonds in the HBr molecules are

• broken as energy is absorbed

• broken as energy is released

• formed as energy is absorbed

• formed as energy is released

Which diatomic molecule is formed when the two atoms share six electrons?

• $H_2$

• $N_2$

• $O_2$

• $F_2$

Which property is used to determine the degree of polarity between two bonded atoms?

• density

• electronegativity

• pressure

• temperature

What is the number of electrons shared between the atoms of an  $I_2$   molecule?

• 7

• 2

• 8

• 4

What is formed when two atoms of bromine bond together?

• a monoatomic molecule

• a diatomic molecule

• a heterogeneous mixture

• a homogenous mixture

Which pair of atoms is held together by a covalent bond?

• HCl

• LiCl

• NaCl

• KCl

Which type of bond is formed between the carbon atom and the oxygen atom in  $CH_3OH$  

• ionic

• electrovalent

• polar covalent

• non-polar covalent

Which substance contains nonpolar covalent bonds?

• $H_2$

• $H_2O$

• $Ca\left(OH\right)_2$

• CaO

Which statement explains why a C-O bond is more polar than an F-O bond?

• At STP, carbon has a greater density than

  fluorine.

• A carbon atom has more valence electrons than a

  fluorine atom.

• the difference in electronegativity between

  carbon and oxygen is greater than that

  between fluorine and oxygen.

• The difference in first ionization energy between

  carbon and oxygen is greater than that between

  fluorine and oxygen

Which formula represents a nonpolar molecule containing polar covalent bonds?

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