2774. In compressed air tunneling, the volume of free air provided is______________? September 7, 2025 by Admin A. 6 mJ per second per m2 of face area B. 6 m3 per minute per m2 of face area C. 20 m3 per minute per m2 of face area D. 6 m3 per hour per m2 of face area ✅ The correct answer is option B.