Grade 9

What is the atomic number of carbon?

• 6

• 8

• 10

• 12

What is the atomic number of chlorine?

• 6

• 8

• 11

• 17

What is the electronic configuration of oxygen?

• 2.4

• 2.6

• 2.8.1

• 2.8.8.1

What is the valency of nitrogen?

• 3

• 2

• 1

• 0

What does octet mean?

• having 2 electron in its outer most orbit.

• having 8 electron in second orbit.

• having 8 electron in its outer most orbit.

• having 2 electron in first orbit.

What is the molecular formula of sodium chloride?

• SoCl

• SCl

• Na₂Cl

• NaCl

What is the molecular formula of aluminium oxide?

• Al₂O₃

• AlO

• Al2O

• AlO3

Argon is an inert gas because ______________ .

• its octet is completed.

• it does not react with other substances

• its valency is zero

• all of the above

What is the name for an ion when it gains an electron.

• Anion

• Cation

How many valence electrons are in an atom of Ar?

• 2
• 8
• 4
• 1