A pure substance is matter that consists of matter with a composition that

• is fixed in a definite proportion at all time.

• varies according to the amount of water present

• always contains two or more substances

• depends on the temperature

Which of the following chemical formulas represents a compound? 

• C₃

• CH₃CHO

• O₂

• H₂

If the pressure in a balloon remains constant what happens to the balloon's volume as the temperature of the air increases?

• the volume decreases and the balloon shrivels up or shrinks

• the volume increases and the balloon expands

• the volume stays the same and the balloon stays the same size

What is the total number of atoms in an ammonia (NH₃) molecule?

• 4

• 3

• 1

• 5

Which of the following elements is a metal?

• Na

• C

• P

• Si

What are the group 18 elements called?

• Alkali Metals

• Alkaline Earth Metals

• Noble gases

• Halogens

Which of the following elements would behave most similarly to Chlorine?

• Argon

• Sulfur

• Fluorine

• Oxygen

Which subatomic particle has a positive charge?

• quark

• proton

• electron

• neutron

What determines an element's identity?

• neutrons

• protons and neutrons

• protons

• electrons

Which statement best describes an element?

• made from a mixture

• thousands in the world

• can be separated

• pure, made of only one type of atom