Which of these substances is acidic?

• tap water
• lemon
• ammonia
• baking soda

What is the most likely pH of a tube of toothpaste?

• 3
• 5
• 7
• 9

How is a standard hydrogen atom different from a hydrogen ion?

• a hydrogen ion has an extra electron.
• a hydrogen ion is missing an electron.
• a hydrogen ion has an extra proton.
• a hydrogen ion is missing a proton.

What might happen if you mixed a strong acid with an equally strong base?

• You would see an explosive chemical reaction.
• The acid would destroy the base.
• The base would destroy the acid.
• You'd wind up with a pH-neutral substance.

An extremely strong base would have a pH of:

• 1
• 7
• 9
• 14

What might happen if buffers did not exist within the human body?

• Our blood and other bodily fluids might become too acidic or basic.
• Our stomach acid would not be able to break down food.
• We would not be able to process glucose within our cells.
• We would not be able to inhale oxygen into our lungs.

This piece of pH paper has been dipped into:

• An acid
• A base
• A pH-neutral substance
• A buffer

Why do metals dissolve when you dip them in acid?

• The buffers in the metal are eaten away by the acid.
• The electrons in the metal are stripped away by hydrogen ions.
• The hydrogen ions in the acid react with the hydroxyl ions in the metal.
• The acid reacts with the basic metal to form carbon dioxide gas and salt.

What might happen if acidi chemicals were emitted into the air by factories?  Choose the best answer.

• The acid would destroy metallic elements in the air.
• The acid would be neutralized by bases within clouds.
• Acid rain might destroy ecosystems and farmland.
• Violent chemical reactions would take place within the atmosphere.

Healthy environments for life have a pH closest to:

• 1
• 3
• 7
• 10