Question

1. which pair of formulas illustrates the law of multiple proportions? (3pts) $square$ ch₄ and c₂h₅oh $square$ koh and naoh $square$ cuo and cuo₂ $square$ h₂o and hno₃

Explanation:

The Law of Multiple Proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element are in a ratio of small whole numbers.

1. For $\text{CH}_4$ and $\text{C}_2\text{H}_5\text{OH}$: They contain three elements (C, H, O), so the law does not apply here.
2. For $\text{KOH}$ and $\text{NaOH}$: These are different ionic compounds with different cations, so they do not represent two compounds of the same two elements.
3. For $\text{CuO}$ and $\text{CuO}_2$: These are two compounds formed by copper (Cu) and oxygen (O). For a fixed mass of Cu, the ratio of O atoms (1:2) is a small whole number ratio, fitting the law.
4. For $\text{H}_2\text{O}$ and $\text{HNO}_3$: They contain different sets of elements (H,O vs H,N,O), so the law does not apply.

Answer:

$\boldsymbol{\text{CuO and CuO}_2}$