Chapter 6, Problem 8STP

Interpretation Introduction

Interpretation: The compounds with same empirical formula need to be determined.

Concept Introduction: The empirical formula is the simplest ratio of atoms of elements present in the compound. It does not tell about the actual number of atoms present in it. Some molecules have empirical formula equal to their molecular formula.

Answer to Problem 8STP

Correct Answer: Option B.

Explanation of Solution

The first pair of compounds is ${\text{H}}_{\text{2}}\text{O}$ and ${\text{H}}_{\text{2}}{\text{O}}_2$ . Here, the molecular formula of water that is ${\text{H}}_{\text{2}}\text{O}$ is also its empirical formula as H and O atoms are present in their simplest ratio. In case of hydrogen peroxide or ${\text{H}}_{\text{2}}{\text{O}}_2$ , the molecular formula can be further simplified to HO which is empirical formula of hydrogen peroxide.

Thus, ${\text{H}}_{\text{2}}\text{O}$ and ${\text{H}}_{\text{2}}{\text{O}}_2$ does not have same empirical formula.

The second pair is ${\text{N}}_{\text{2}}{\text{O}}_{\text{4}}$ and ${\text{NO}}_{\text{2}}$ . The empirical formula of both the compounds will be ${\text{NO}}_{\text{2}}$ . Thus, they have same empirical formula.

The third pair is CO and CO₂. Here, both the compounds have same empirical formula as their molecular formula. Thus, both have different empirical formula.

The fourth pair is CH₄ and C₂H₆. The second formula can be simplified to CH₃ which is different from the first formula. Thus, they do not have same empirical formula.

Conclusion

Therefore, option (B) is correct.