A student read that a block has a density of .70g/cm^3. When she tested this she got .63g/cm^3. What is her percent error

Explanation:

The percentage error of a certain measurement can be found by using the formula

From the question

actual density = 0.7 g/cm³

error = 0.7 - 0.63 = 0.07

So we have

We have the final answer as

Hope this helps you

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.