4. When the mole fraction of solute is 1, there is (a) a 1:1 ratio of solute to solvent.
(b) no solute present.
(c) only solute present.
(d) only solvent present.
(e) 1 mole of solute and 99 moles of solvent.

(c) only solute present

Explanation:

In chemistry, the mole fraction, denoted by X, refers to the number of moles of a substance in a compound/mixture divided by the total number of substances in the same compound or mixture.

In this case, we can say that mole fraction represents the number of solutes to the number of solutes and solvent in the solution i.e. X = nA/nA + nB

Where; nA = number of solutes

nB = number of solvent

X = mole fraction.

Based on this analogy, When the mole fraction of solute is 1, there is only solute present. That is; X = 1 / 1 + 0

X = 1/1 = 1.

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 !

im pretty sure its b