What is the glass-like substance produced when the heat from an arc melts silica sand in a current limiting fuse?

The correct answer is B, Fulgurite. Fulgurite is a naturally occurring glass that forms when lightning strikes sand or soil, resulting in the rapid melting and then solidification of silica. In the context of a current limiting fuse, when the arc from the electric current melts the silica sand, it creates a substance similar to fulgurite due to the intense heat and rapid cooling process, resulting in a glass-like formation.

While quartz is a common crystalline form of silica, it doesn’t form in this scenario, as it represents the solid, natural crystal rather than a glass-like structure produced from melting. Silicate, on the other hand, refers to a broader category of minerals that include silica, but it does not specifically describe the glassy substance created by melting. Obsidian is another form of volcanic glass, but it is formed from lava rather than through an arc process involving silica sand. Therefore, fulgurite is specifically linked to the melting of silica sand by an intense heat source like an electric arc, making it the accurate answer here.