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.
Seven of the world's longest railway tunnels are located in Asia, including four in Japan and two in China. Europe is home to three of the 10 longest, including the UK's Channel Tunnel. Railway-technology.com profiles the world's longest railway tunnels. The 53.85km Seikan tunnel in Japan is the longest and deepest rail tunnel in the world.