Which statement is true about a molecule with the molecular formula C10H20, that when subjected to catalytic hydrogenation there is no consumption of hydrogen?

a. The molecule has no degrees of unsaturation.
b. There is one degree of unsaturation, which happens to be a pi-bond.
c. There are two degrees of unsaturation where one is a ring and the other is a pi-bond.
d. There is one degree of unsaturation, which happens to be a ring.
e. None of the above.

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

the electron configuration that you gave me has 16 electrons ergo it has 16 protons ergo it is the element sulfur.