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.
Asia's longest bi-directional road tunnel, the Chenani-Nashri Tunnel is a part of the Jammu-Srinagar Highway's four-laning project. Twelve similar projects are in the pipeline, to reduce the travel time and distance within J&K. This tunnel is at an elevation of 1,200 metres, and was built at an expense of Rs 2,519 crore.