A(n) is an assemblage of minerals bound together, a mass composed of a single mineral, a mass of undifferentiated materials, or a mass of solid organic material.

Rock

Explanation:

Rock -

It refers to the naturally occuring mass of mineral , with a uniform chemical composition , is referred to as a rock .

In the crust of the Earth , the composition is by the igneous rocks .

There are three main type of rocks , i.e. ,

Hence , from the given information of the question ,

The correct term is rock.

altitude, density, pressure

air gets less dense the higher the altitude and also the air pressure is less as altitude rises.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !