Forming a chemical bond releases energy and therefore is an exothermic process. Exothermic reactions usually feel hot because it is giving heat to you. Endothermic-a process or reaction that absorbs energy in the form of heat. Breaking a chemical bond requires energy and therefore is Endothermic.
karma level 71199. The Seikan Tunnel is a 53.85 km (33.46 mi) railway tunnel in Japan, with a 23.3-kilometre (14.5 mi) long portion under the seabed. Track level is about 140-metre (460 ft) below seabed and 240-metre (790 ft) below sea level. It is the longest undersea tunnel in the world, although the Channel Tunnel between the United Kingdom and France has a longer under-sea portion.
Gotthard Tunnel: World's longest rail tunnel officially opens with eclectic opening ceremony. Photo: Guests look at screens during the opening ceremony of the Gotthard tunnel. The world's longest tunnel has officially been opened in Switzerland with an elaborate ceremony featuring an eclectic range of performance art. 1  The Gotthard Base Tunnel cuts through the Swiss Alps easing travel and trade.  The 57km tunnel took 17 years to complete and cost over $16 billion.