What is the mass of 50mL of water when you dont know the density

13.09 g

Explanation:

To determine mass, subtract the mass of the empty cylinder from the mass of the cylinder plus liquid. The mass of the liquid is 13.09 g . In this question, volume is measured in milliliters, mL , and mass is measured in grams, g. Substitute your known values into the density equation and solve.

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.