The location where the mercury level of the barometer would be the lowest is at the very high altitudes of the Earth's atmosphere (about 100 km), since air pressure decreases as altitude increases.
It is avogrado number. One molecue of magnesium has 6.023 x 10^23 atoms
Answer:
fe3o4+4h2 - 3fe + 4h2o
therefore coefficient is 4
