Final answer:
Nitroglycerin is mentioned in the context of tunneling through mountains, which indicates it is used as an explosive for construction. The term's dual use in medicine and construction is an example of a chemical's versatility. Context clues suggest nitroglycerin was essential for projects like railroad construction that involve rock blasting.
Step-by-step explanation:
The use of nitroglycerin to tunnel through mountains implies that it has capabilities as an explosive. Context clues within lines 198-203 of Chang's reference likely describe the process of using nitroglycerin in construction, particularly in the excavation of hard terrain like mountains. The phrase 'tunnel through mountains' itself suggests the need for a powerful agent to break through such difficult geological formations. Moreover, if the text aligns with historical usage, nitroglycerin was commonly employed in the 19th century for construction of railroads and other major infrastructure projects, requiring the blasting of rocks and earth.
Despite its explosive properties, nitroglycerin is also known in another, vastly different context: as a medicine to relieve chest pain in heart disease. This dual use speaks to the substance's versatility and the importance of understanding chemical compounds in different applications. It's crucial for a student learning this information to grasp the historical use of nitroglycerin in construction, the dangers associated with handling it, and its application in healthcare.
Within the given additional reference, picture a shows the process of cutting a metal railroad tie with an acetylene torch, which may relate to the construction theme, while picture b depicts a chemical cold pack that contains ammonium nitrate, another compound with applications in both medical and industrial fields, similar to nitroglycerin.