Biology

Ice floats on water because

• of cohesion.
• ice has a higher density than water.
• water shrinks when it freezes.
• water expands when it freezes.

The most abundant compound in most living things is

• carbon dioxide
• water.
• sodium chloride.
• sugar.

Water molecules are polar, with the

• oxygen side being slightly positive and the hydrogen side being slightly negative.
• oxygen and hydrogen sides being slightly positive.
• oxygen and hydrogen sides being slightly negative.
• oxygen side being slightly negative and the hydrogen side being slightly positive.

A solution is a(an)

• combination of isotopes.
• chemical reaction.
• evenly distributed mixture of two or more substances.
• combination of two or more liquids.

If you stir salt into boiling water, you produce a

• mixture called a suspension.
• mixture called a solution.
• solution and suspension.
• mixture only.

When salt is dissolved in water, water is the

• reactant.
• solution.
• solute.
• solvent.

While preparing a cell culture, a scientist places a colony of bacteria into distilled water and stirs it up. This mixture of water and living cells would best be called a(an)

• solution.
• suspension.
• buffer.
• adhesion.

Tags

NGSS.MS-PS1-2

If the pH of stomach acid and of oven cleaner were measured,

• both would be below 7.
• both would be above 7.
• the pH of stomach acid would be above 7, but the pH of oven cleaner would be below 7.
• the pH of stomach acid would be below 7, but the pH of oven cleaner would be above 7.

A substance with a pH of 6 is called

• an acid.
• a base.
• both an acid and a base.
• neither an acid nor a base.

Solutions that contain concentrations of H⁺ ions lower than pure water

• have pH values below 7.
• are acids.
• are bases.
• are enzymes.