Biology Chapter 2 Water and pH

What two elements make up water?

• Helium and oxygen
• Hydrogen and oxygen
• helium and carbon
• oxygen and carbon

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NGSS.MS-PS1-1

What word describes when water is attracted to other substances?

• cohesion
• adhesion
• capillary action
• surface tension

Attractions between the negative Oxygen atom of one water molecule and the positive Hydrogen atom of another water molecule are called

• Covalent bonds
• Ionic bonds
• Polar bonds
• Hydrogen bonds

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NGSS.MS-PS1-1

Why does ice float?

• As water freezes, it expands and its density decreases.
• As water freezes, it takes up more hydrogen from the atmosphere, causing it to have a greater buoyancy.
• As water freezes, air becomes trapped between the hydrogen bonds of water molecules.
• As water freezes, it takes up more oxygen from the atmosphere, causing it to have a greater buoyancy.

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NGSS.MS-PS1-4

Which end of the water molecule has a slightly positive charge?

• the oxygen end
• the hydrogen end
• both ends are slightly positive
• neither end is positive

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NGSS.HS-PS1-3

Water is a universal solvent because it...

• It can be found anywhere
• It freezes when it gets cold
• floats when frozen
• Dissolves most substances

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NGSS.MS-PS1-2

Which of the following is LEAST likely to dissolve in water?

• nonpolar fats and oils
• polar sugar molecules
• salt made of a positive sodium ion and a negative chloride ion
• all of the substances will dissolve easily in water

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NGSS.HS-PS1-3

Large bodies of water, such as lakes and oceans, do not quickly fluctuate in temperature. What is the reason for this phenomenon?

• Water is an acid.
• Water is a versatile solvent.
• Water has a high heat capacity.
•  Water acts as a buffer.

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NGSS.HS-ESS2-5

 Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens?

• The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together
• The insects actually use their wings to hover slightly above the water's surface and they only skim it with their feet
• The insects' feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water's surface
• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next

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NGSS.MS-PS2-5

A(n) ______ is a substance with a pH less than 7

• Acid
• Alkaline
• Base
• Buffer