Answer:
Hot chocolate is as straightforward as drinks go: at its core, it's milk, cocoa powder, and sugar. Despite its simplicity, this cold-weather classic is swirling with science. The backbone of any decent hot chocolate is milk. Beyond water, milk is perhaps the most basic and familiar substance to humans.
The answer is 1.5*10^-12 square meters. For a detailed calculation, please refer to the attachment.
