Sedimentary rocks form where there is water, like streams, rivers and the coast. At the Great Unconformity, sedimentary rocks form near the top as they are younger.
Metamorphic rocks form where there is extreme pressure and/or heat, such as deep underground or in a volcano. At the Great Unconformity, metamorphic rocks are at the bottom as they are older.
The answer is (3) 53.5 g/mol. The gram formula mass means that the mass of one mol compound. 1N=14, 4H=4, 1Cl=35.5. So the gram formula mass of NH4Cl=14+4+35.5=53.5 g/mol.