What is one disadvantage of carbon-zinc cells?

The disadvantage of carbon-zinc cells being a high self-discharge rate is rooted in their design and chemistry. Carbon-zinc batteries, commonly known as dry cells, experience a significant loss of charge when not in use. This self-discharge occurs due to the chemical reactions within the battery, which can lead to a considerable decrease in stored energy over time, even if the battery is not connected to a circuit.

In practical applications, this means that if carbon-zinc batteries are stored for a long duration without being used, they may not perform as expected when needed. This characteristic limits their effectiveness in scenarios where long-term storage is anticipated or where reliability is critical.

Other options do have their merits but do not specifically highlight the significant concern associated with self-discharge. For instance, while uneven power discharge can occur, it is not a defining characteristic of carbon-zinc cells compared to issues seen in other battery types. High cost is also not generally associated with carbon-zinc cells, as they are typically some of the more economical batteries available. Lastly, while carbon-zinc cells do have lower voltage outputs compared to certain alkaline or lithium batteries, this aspect does not directly relate to the self-discharge issue as a major disadvantage.