Chemistry Review 1

Which of the following properties uniquely identifies every element?

• Number of valence electrons
• Phase at room temperature
• Number of protons
• Charge of the atom

• 2
• 4
• 6
• 8

• A
• B
• C
• D

• A
• B
• C
• D

According to the Law of Conservation of Mass,

• matter is always created in a chemical reaction.
• matter is always destroyed in a chemical reaction.
• matter is created and then destroyed in a chemical reaction
• matter is not created or destroyed in a chemical reaction.

How many oxygen products are listed in the chemical equation below,
2Mg + O_{2 ------>} 2MgO

• 0
• 1
• 2
• 4

In which of the following examples has a chemical reaction occurred?

• After putting liquid batter into a hot pan, the batter solidifies and begins to turn brown.
• After turning on a blender filled with fruits, the fruit is chopped up and mixed together.
• After taking a tray filled with ice cubes out of the freezer, the cubes begin to melt.
• After adding a spoonful of sugar to a mug of hot coffee, the sugar dissolves completely.

When vinegar and baking soda are combined, bubbles begin to form.  Bubbles are evidence of a chemical reaction because they - 

• pop when they are touched.
• show that a gas is forming.
• form at a fast rate.
• are generally transparent.

Which of the following substances are elements?

• water

• salt

• carbon dioxide

• hydrogen

How many elements are in this Carbon dioxide molecule?

• 3

• 2

• 1

• 0