Which is the most accurate description of compounds?
a. they are not pure substances.
b. they are made of only 1 type of atom.
c. they are the basic building blocks of matter.
d. they are made up of atoms of 2 or more elements that are chemically combined.

Option (d) is the correct answer.

Explanation:

A compound is defined as the substance in which only different atoms chemically combine together in a fixed ratio by mass.

For example, NaCl, HCl, , etc are all compounds.

Compounds are also pure substances like elements as they can be broken down into their constituent particles.

Whereas substances that are made up of only one type of atom are known as elements.

Thus, we can conclude that the most accurate description of compounds is that they are made up of atoms of 2 or more elements that are chemically combined.

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g