PKS_Atoms & Molecules_Grade_9

1. The atomic number of an element X is 13. What will be the number of electrons in its ion X³⁺?

• 11

• 15

• 16

• 10

Which of the following represents a correct chemical formula?

• CaCl

• Na3N
  

• NaSO4

• NaS

If the number of electrons in an ion X^3- is 10., atomic number of element X would be?

• 7

• 10

• 5

• 8

How many carbon atoms are there in a methane molecule? 

• 0
• 1
• 4
• 5

What is the chemical symbol for the element mercury?

• Hg

• Merc

• MeC

• MY

What do you call the 2 in 3CO₂?

• Coefficient
• Subscript
• Element
• Small

Explain the difference between an atom and a molecule.

• One molecule is made of one atom.
• One molecule is always made of different particles.
• One molecule is made of more than one atom.
• One molecule is made of more than two atoms.

Carbon dioxide (CO₂) contains how many atoms of oxygen?

• 0
• 1
• 2
• 3

What are the states of matter?

• Solid, Liquid, Water
• Solid, Liquid, Gas
• Melting, Freezing, Condensing, Evaporating
• Water and Liquid

Atoms that have the same number of protons but different numbers of neutrons.

• Isotopes
• Neutron
• Proton
• Atomic Mass