How much NaCl would you dissolve and dilute to the 100.00 mL mark in a volumetric flask with DI H2O to prepare a 0.825 M sodium chloride solution?

4.82 g

Explanation:

To solve this problem we'll use the definition of molarity:

We are given the volume and concentration (keep in mind that 100mL=0.100L):

Now we calculate the number of NaCl moles required:

Then we convert 0.0825 NaCl moles into grams, using its molar mass:

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.