Final answer:
The longest mountain chain is the Andes mountain range in South America, with the highest peak being Mount Aconcagua in Argentina.
Step-by-step explanation:
The longest mountain chain in the world is the Andes mountain range, which stretches about 7,000 kilometers along the western coast of South America, through seven countries including Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina. The Andes is also home to the highest peak in the Western Hemisphere, Mount Aconcagua, which is located in Argentina. It reaches a height of 6,960.8 meters (22,837 feet) above sea level.
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