Final answer:
The question "How many continents are there on Earth?" cannot be easily answered with a binary response, unlike asking for the capital of France, the composition of water, and the square root of 64.
Step-by-step explanation:
Among the four provided questions, the one that cannot be easily answered using a binary set of answers such as yes or no is: "How many continents are there on Earth?" This question requires a numerical answer rather than a binary one. On the other hand, the questions regarding the capital of France, the composition of water, and the square root of 64 can all be responded to with a definitive answer, hence they can be tested using the scientific method.
To elaborate further, asking for the capital of France requires a specific name as an answer; whether water is composed of hydrogen and oxygen is a question about its chemical makeup which can be confirmed through scientific analysis; and the square root of 64 has a precise mathematical answer. The question about the number of continents involves geography and might vary based on different perspectives due to cultural and historical differences in counting the number of continents.