Question

which of the following statements about empirical formulas are false:
i. empirical formulas are the smallest possible whole number ratio of atoms in a compound.
ii. the empirical formula and molecular formula cannot be the same ratio.
iii. different molecular formulas cannot have the same empirical formula.
iv. the empirical formulas of benzene (c₆h₆) and acetylene (c₂h₂) are the same.

○ i, ii, iv
○ i, iv
○ all are false
○ ii, iii

Explanation:

Step1: Analyze Statement I

The definition of an empirical formula is the simplest whole - number ratio of atoms in a compound. So statement I is True.

Step2: Analyze Statement II

For some compounds, like water ($\ce{H_2O}$), the empirical formula and the molecular formula are the same (the ratio of H to O in the empirical formula is 2:1, and in the molecular formula is also 2:1). So the statement "The empirical formula and molecular formula cannot be the same ratio" is False.

Step3: Analyze Statement III

For example, benzene ($\ce{C_6H_6}$) and acetylene ($\ce{C_2H_2}$) have different molecular formulas but the same empirical formula ($\ce{CH}$). Also, $\ce{C_2H_4}$ (ethene) and $\ce{C_3H_6}$ (propene) have different molecular formulas but the same empirical formula ($\ce{CH_2}$). So the statement "Different molecular formulas cannot have the same empirical formula" is False.

Step4: Analyze Statement IV

For benzene ($\ce{C_6H_6}$), the ratio of C to H is 6:6 = 1:1. For acetylene ($\ce{C_2H_2}$), the ratio of C to H is 2:2 = 1:1. So their empirical formulas (the simplest whole - number ratio) are both $\ce{CH}$, so statement IV is True.

So the false statements are II and III.

Answer:

II, III