Evidence of Chemical Reactions Answers

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Which indicator most likely suggests that a chemical change is taking place?

change in size

change of color

change of state

change in shape

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The images show two unrelated events occurring at separate times. Which event is most likely an example of a chemical reaction?

Event 1 because there is a color change.

Event 1 because there is a release of heat and light.

Event 2 because the temperature is dropping in the liquid.

Event 2 because the blue color mixes throughout the liquid.

Two different liquids are mixed together. Which observation indicates that an exothermic chemical reaction has taken place?

an increase in volume

a decrease in volume

a rise in temperature

a drop in temperature

Burning a piece of wood in fire can be best described as a

chemical change because the atoms in wood change their state.

physical change because the atoms in wood are turned into a gaseous product.

chemical change because the atoms in wood and oxygen are rearranged.

physical change because the atoms in wood are turned into black ash.

A piece of limestone erodes due to acid rain. This process can be best described as a

slow chemical change.

rapid chemical change.

slow physical change.

rapid physical change.

The chemical formula below shows how salt is produced.HCl + NaOH NaCl + H2O Which substances are the reactants?

HCl and NaCl

NaCl and H2O

HCl and NaOH

NaOH and H2O

The images show two processes. Image A: a roasting marshmallow Image B: melting iceWhich statement about the two images is true?

Image A shows a physical change, and image B shows a chemical reaction.

Image A shows a chemical reaction, and image B shows a physical change.

Both images show chemical reactions that are endothermic.

Both images show chemical reactions that are exothermic.

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