Final answer:
The relationships between the compounds are: Compound pairs X and Y, R and S are constitutional isomers; P and Q are constitutional isomers as well; A and B are diastereomers; M and N are identical.
Step-by-step explanation:
The relationship between the compounds in each pair is as follows:
- Compound X: CH₃CH₂OH, Compound Y: CH₃OCH₃ - These are constitutional isomers because they share the same molecular formula but have different arrangements of atoms, specifically in regards to their functional groups (alcohol and ether, respectively).
- Compound P: CH₃CH₂CH₂CH₃, Compound Q: CH₃CH(CH₃)₂ - These are also constitutional isomers. They are isomers of butane: one is n-butane and the other is isobutane (or methylpropane), differing in the branching of the carbon chain.
- Compound A: CH₃CH₂CH₂OH, Compound B: CH₃CHOHCH₃ - These are diastereomers since they have the same molecular formula and are stereoisomers (differ in spatial arrangements of atoms) but are not mirror images of each other.
- Compound M: CH₃CH₂CH₂CH₃, Compound N: CH₃CH₂CH(CH₃)₂ - These two are identical; they are both isobutane and thus no isomerism is present.
- Compound R: CH₃CH₂OH, Compound S: CH₃CHOHCH₃ - These are constitutional isomers, where R is ethanol and S is isopropanol. They have the same molecular formula but differ in the connection sequence of their atoms and the placement of their functional groups.