sec 2 lesson 4

What is the number of the lone pairs of electrons on arsenic atom ₃₃As in arsine AsH₃?...............

• Zero  

• 1

• 2

• 3

The opposite figure represents a/an …………… compounds.

• ionic

• polar covalent

• pure covalent

• acidic

The covalent bonding in methane molecule CH₄ requires …………… electrons.

• 10

• 8

• 4

• 2

According to VSEPR, the presence of 4 bond pairs of electrons around the central atom causes the molecule to have the stereostructure.

• linear

• planar triangle

• angular

• tetrahedron

Which of these statements explains why atoms of neon do not form ionic bonds?   

• Atoms of neon have delocalised electrons

• Atoms of neon must gain or lose four electrons to form a stable octet in their outer shell

• Atoms of neon already have a stable octet in their outer shell.

Which of the following pairs of compounds are similar in their molecular Stereostructure?

• BF3 , NH3  

• BeCl2 , H2O

• CCl4 , CH4

• PF3 ,IF3

Which of the following compounds molecules contains 2 bond pairs and 2 lone pairs of electrons? 

• NH3

• SO2

• H2S

• BF3

The opposite graphical figure illustrates the melting points of different elements, among which is sodium , which of the illustrated Setters represents sodium element?

• A

• B

• C

• D

Three students assumed three factors which affect the strength of the hydrogen bond:

 Factor (1): The angle between the hydrogen bond polar bond in the same molecule.

 Factor (2): The number of bond pairs of electrons in the central atom.

 Factor (3): Difference in electronegativity between the hydrogen atom and the other atom binded to it.

Which of these factors are correct? ...............

• (1) , (2)

• (1) , (3) 

• (2) , (3) 

• (1) , (2) and (3)

Molecules of HF , H2O and NH3 are all able to form hydrogen bonds.

What property of a molecule gives it the ability to form a hydrogen bond?

• A large difference in electronegativity between hydrogen and the atom it is bonded to

• The number of hydrogen atoms covalently bonded to an atom of a different element

• The ability to conduct electricity in aqueous solutions