Final answer:
Water (H₂O) is the correct answer as it is a weak nucleophile, having a neutral charge and less readily available electron pairs compared to the other options listed which are either strong nucleophiles or not nucleophiles at all.
Step-by-step explanation:
The question asks to identify which of the listed compounds is a weak nucleophile. A weak nucleophile is generally neutral or has a full positive charge and has a less readily available electron pair for bonding. Among the options listed:
- (a) OH-: This is a strong nucleophile as it has a negative charge and readily available electron pair.
- (b) H₂O: Water is a weak nucleophile due to its neutral charge and the fact that its lone pairs are less accessible due to the electronegativity of oxygen.
- (c) CH₃O-: Similar to OH-, this is a strong nucleophile because of its negative charge and available electron pair.
- (d) NH₄+: Ammonium ion is not a nucleophile at all, as it has a full positive charge with no available lone pairs.
- (e) All of these: This option is incorrect because not all the options listed are weak nucleophiles.
The correct answer is (b) H₂O.