Answer:
(c) and (d)
Explanation:
The law of definite proportions states that elements in compounds always have a fixed atomic ratio independent of any conditions.
In the context of this problem, we only know the mass ratio of X to Y, but we don't know the molar ratio, so we cannot derive the empirical formula.
However, we notice that in the second compound, mass of Y increased by a fraction of:
[tex]\frac{5.946}{1.982} = 3[/tex]
Since mass is directly proportional to moles, in the second compound we should have three times larger number of atoms of Y for the same number of atoms of X (1 part in each case lets us assume this).
a. Notice that X is kept constant and Y increases by a factor of 3, so it's consistent.
b. Similarly to (a), X is kept constant and Y increases by a factor of 3, so it's consistent.
c. Here, Y is kept constant. X increases by a factor of 3. This is inconsistent with the data, since if we start with [tex]XY[/tex], then we'd have [tex]XY_3[/tex] as our second pair, since we should have three times greater number of Y atoms in the second structure.
d. The molar ratio here in each pair is the same, XY is the empirical formula for [tex]X_3Y_3 = (XY)_3[/tex]. This means it's inconsistent, as here both formulas have the same ratio of X to Y.
e. This is consistent, since for a constant Y, in the second structure we should have one third of X atoms to obtain the 3 : 1 ratio.
