How do i begin this problem? how do i set up the problem? what formula do i use?

Classify this reaction: 2al+n2-> aln.

Which of the following natural processes is most likely to support the formation of an underwater sinkhole? a pollution buildup from deposited minerals b limestone cave collapsing due to changes in sea level c erosion of large amounts of sand moved by ocean waves d oxidation of rock formed by chemical weathering

What was bohr’s contribution to the planetary model