(1) Andes mountains Explanation: A mountain range, or ‘mountain belt’, is a geographic area containing numerous geologically related mountains. Above sea level the Andes is usually considered the world’s longest mountain system; it is 7,000 kilometres in length. The Himalaya Range contains the highest mountains on the Earth’s surface, the highest of which is Mount Everest. The world’s longest mountain system is known as Ocean Ridge, which is a chain of mountains that runs on the seafloor of five oceans around the world; it has a length of 65,000 kilometres, and the total length of the system is 80,000 kilometres. The Andes is the world’s longest mountain system on the surface of a continent; it is 7,000 kilometres in length.