Elements, Compounds and Mixtures

What is an element?

• A pure substance that cannot be broken down into two or more simpler substances by chemical processes.

• An impure substance that cannot be broken down into two or more simpler substances by chemical processes.

• A pure substance that can be broken down into two or more simpler substances by chemical processes.

• An impure substance that can be broken down into two or more simpler substances by chemical processes.

Which is NOT an element?

• Carbon

• Copper

• Oxygen

• Carbon dioxide

Which is the correct symbol for Hydrogen?

• Hg

• H

• He

Which list contains three elements?

• Air, Nitrogen, Oxygen

• Brass, Solder, Steel

• Carbon, Iron, Zinc

• Hydrogen, Oxygen, Water

Diatomic molecules are those formed by the combination of two atoms. Which of the following is a diatomic molecules?

• P₄

• O₃

• S₈

• N₂

Which is a compound?

• X

• Y

• Z

• W

Ammonium carbonate is a salt with the chemical formula (NH₄)₂CO_3. What is the number of elements in ammonium carbonate?

• 2

• 3

• 4

• 5

Which of these elements is a monatomic?

• Ar

• N₂

• H₂

• P₄

How many N atoms are there in Pb(NO₃)₂?

• 2

• 3

• 4

• 5

Which of the following represents an element?

• H₂O
• H₂
• NaCl
• CaCO₃