Intro to Chemistry

What is a physical change?

• A physical change is a change in which the substance involved remains the same, but its physical properties, such as shape, size, or state, are altered.

• A physical change is a change in which the substance involved becomes a completely different substance.

• A physical change is a change in which the substance involved is destroyed.

• A physical change is a change in which the substance involved undergoes a chemical reaction.

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Give an example of a physical change.

• Burning wood

• Melting ice

• Boiling water

• Mixing salt and water

What is a chemical change?

• A chemical change is a process that results in the formation of new substances with opposite properties from the original substances.

• A chemical change is a process that results in the formation of new substances with no properties.

• A chemical change is a process that results in the formation of new substances with different properties from the original substances.

• A chemical change is a process that results in the formation of new substances with the same properties as the original substances.

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Give an example of a chemical change.

• Melting of ice

• Mixing of salt and water

• Burning of wood

• Cutting a piece of paper

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What is the difference between a physical change and a chemical change?

• The difference between a physical change and a chemical change is that a physical change does not involve a change in chemical composition, whereas a chemical change does.

• A physical change can be reversed, whereas a chemical change cannot.

• A physical change involves a change in temperature, whereas a chemical change does not.

• A physical change only affects the appearance of a substance, whereas a chemical change affects its properties.

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What is an acid?

• An acid is a chemical substance that has a pH value greater than 7 and donates hydrogen ions (H+) when dissolved in water.

• An acid is a chemical substance that has a pH value of exactly 7 and donates hydrogen ions (H+) when dissolved in water.

• An acid is a chemical substance that has a pH value less than 7 and accepts hydrogen ions (H+) when dissolved in water.

• An acid is a chemical substance that has a pH value less than 7 and donates hydrogen ions (H+) when dissolved in water.

What is the pH scale?

• The pH scale is a measure of acidity or basicity of a solution.

• The pH scale is a measure of temperature.

• The pH scale is a measure of pressure.

• The pH scale is a measure of volume.

What is the pH of a neutral substance?

• 10

• 14

• 7

• 1

What is the pH of an acidic substance?

• negative

• greater than 7

• less than 7

• equal to 7

What are some common examples of acids?

• Water, sugar, salt

• Coffee, bleach, soap

• 
  Vinegar, lemon juice, stomach acid

• Orange juice, battery acid, milk