REVIEW PYPQ

Which molecules have an overall dipole moment?

• carbon monoxide, CO

• phosphine, PH₃

• carbon dioxide, CO₂

The greater the difference between the electronegativities of the two atoms in the bond, the more polar is the bond. Which pair will form the most polar covalent bond between the atoms?

• chlorine and bromine

• chlorine and iodine

• fluorine and chlorine

• fluorine and iodine

Which molecule has the largest overall dipole?

• A

• B

• C

• D

What are the bond angles in the PH₃ molecule likely to be?

• 90

• 104.5

• 109.5

• 120

Which pair has species with different shapes?

• BeCl₂ and CO₂

• CH₄ and NH₄⁺

• NH₃ and BF₃

• SCl₂ and H₂O

Which statements about bond angles are correct?

• The bond angle in SO₂ is smaller than the bond angle in CO₂.

• The bond angle in H₂O is smaller than the bond angle in CH₄.

• The bond angle in NH₃ is smaller than the bond angle in BF₃.

Each of the four species in this question are isolated and gaseous. Which species is not planar?

• BF₃

• CH_3⁺

• C₂H₄

• NH_3

Sodium borohydride, NaBH₄, and boron trifluoride, BF₃, are compounds of boron. What are the shapes around boron in the borohydride ion and in boron trifluoride?

• square planar, pyramidal

• square planar, trigonal planar

• tetrahedral, pyramidal

• tetrahedral,trigonal planar

Which compound has the greatest total number of lone pairs of electrons in the valence shells of all of its atoms?

• CH₃Cl

• CO₂

• N₂H₄

• NH₄CN

Magnesium oxide is used to line industrial furnaces because it has a very high melting point.

Which type of bond needs to be broken for magnesium oxide to melt?

• co-ordinate

• covalent

• ionic

• metallic