Final answer:
The statement is true because Tollens' reagent is selective for aldehydes, producing a silver mirror upon reaction, while potassium dichromate can oxidize a broader range of substances.
Step-by-step explanation:
The statement provided is True. Compounds that react with the Tollens' reagent, which primarily identifies the presence of aldehydes, can also react with K₂Cr₂O₇ (potassium dichromate). The key distinguishing factor is that Tollens' reagent is a relatively mild oxidizing agent, reacting with aldehydes to produce a characteristic silver mirror but not reacting with ketones. On the other hand, potassium dichromate is a stronger oxidizing agent that can react not only with aldehydes but also with a wide range of other substances including primary alcohols, secondary alcohols, and sometimes even some types of ketones under appropriate conditions.
This discrepancy arises because aldehydes are easier to oxidize than ketones due to the presence of a hydrogen atom attached to the carbonyl carbon, making them more reactive towards oxidizing agents like the Tollens' reagent. The reaction with K₂Cr₂O₇ involves a different mechanism and has the capability to oxidize a larger variety of chemical compounds.