Which piece of glassware is best suited for making accurate dilutions?

volumetric glassware

Explanation:

A volumetric glassware or capacity flask is a flat-bottomed glass container, it has an elongated and narrow neck, with a capacity that marks where the piping should be performed, which indicates a volume with great accuracy and precision. In the same way as for volumetric pipettes, the neck of the volumetric glassware is relatively thin, so that a small change in volume of the liquid causes a considerable difference in the height of the meniscus; consequently, the mistake made when adjusting the meniscus in the brand is very small.

The volumetric glassware are calibrated to contain the specified volume of liquid at a defined temperature. As the graduation surrounds the entire neck of the flask, it is easy to avoid parallax errors when the liquid is brought to the capacity, aligning the eye so that the closest and farthest sides of the ring are tangent to the lower edge of the meniscus. It is essential that the flask be free of grease, especially at or near the capacity signal. Volumetric glassware are used to prepare solutions of known concentration at exact dilutions.

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.