Revision Chapter 4: Chemical Bonding

Element A and E have two and seven valence electrons respectively. The most likely formula of the compound formed between A and E is

• A₂E

• AE₂

• A₂E₂

• A₂E₇

Which of the following statements about dative bond is correct?

• Each bonded atom supplies one electron to the shared pair of electrons

• A dative bond has the same characteristics as an ionic bond

• A donor atom must have at least one lone pair of electrons and the acceptor atom must have at least one vacant orbital

• Dative bond usually formed between positively and negatively charged ions.

What is the formal charge of the N atom in the nitrate ion, NO₃^-?

(Hint: Draw the Lewis structure of NO₃^- first)

• 0

• -1

• +1

• -2

Which group in Periodic Table does M belong to?

• Group 14

• Group 15

• Group 16

• Group 18

Which of the following species disobeys the octet rule?

• PCl₃

• CH₂Cl₂

• ClO₂^-

• ICl₄^-

Answer explanation

The central atom has 2 lone pairs and 4 bonding pairs, more than octet. Expanded octet

Which of the following pairs do not form dative bond to each other?

• H₂O and H⁺

• NH₃ and BF₃

• NH₃ and H⁺

• AlCl₃ and H⁺

The shape of the molecule SF₄ is best described as

• tetrahedral

• square pyramidal

• see-saw

• octahedral

XH₃ is the gaseous hydride of an element in the Group 15 of the periodic table. Which of the following molecular geometry is most likely for the hydride molecule?

• Trigonal bipyramidal

• Trigonal pyramidal

• Trigonal planar

• Tetrahedral

The H-N-H bond angles in NH₃ are smaller than the H-C-H bond angles in CH₄ because

• NH₃ is trigonal pyramidal in shape whereas CH₄ is tetrahedral

• All electron pairs in NH₃ repel each other equally

• the repulsion of the lone pair of electrons is greater than the repulsion of the bonding pair of electrons

• NH₃ is a polar molecule

Which molecule has polar bonds but zero dipole moment?

• H₂O

• CO₂

• NH₃

• CH₃Cl