Which data can be measured quantitatively? speed of light
odor of gas
texture of a solid
color of a flame

its the first one speed of light

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.