Consider the following statements: 1. Many of the world’s largest mountain chains exist beneath the sea. 2. Some mountain chains are revealed as island arcs. 3. The mid-oceanic ridges form the longest mountain chains. 4. The mid-Atlantic ridge rises thirty-three metres above the floor of the Atlantic. Which of the statements given above are correct?

Statement 1 is correct as many of the world's largest mountain chains, such as the mid-oceanic ridge system, exist beneath the sea [1][4]. Statement 2 is correct because island arcs are narrow chains of volcanic islands or mountains that reveal these submarine structures above the surface, such as the Japanese Islands [3][6]. Statement 3 is correct as the mid-oceanic ridge is the longest mountain chain on Earth, spanning approximately 65,000 to 75,000 km [1][4][7]. Statement 4 is incorrect; the Mid-Atlantic Ridge is a massive geological feature rising about 3 km (3,000 metres) above the ocean floor, not a mere 33 metres [2]. While some peaks reach the surface to form islands like Iceland, the general elevation of the ridge system is significantly higher than 33 metres [2][3].

Sources

1. [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Interior of the Earth > Mid-Oceanic Ridges > p. 29
2. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 31: Ocean Relief > Mid-Oceanic Ridges or Submarine Ridges > p. 482
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 8: Convergent Boundary > Formation of Continental Arcs > p. 116
4. [6] https://whc.unesco.org/en/activities/504/
5. [7] https://www.noaa.gov/jetstream/tsunamis/tsunami-generation-earthquakes/jetstream-max-plate-tectonics-and-earthquakes
6. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 12: Water (Oceans) > Mid-Oceanic Ridges > p. 102