Final answer:
In the fictional Naruto universe, Chakra is a form of energy; no specific amount is detailed for popping a rubber ball. In the real world, the force required to pop a ball is measured in newtons and depends on the ball's physical properties.
Step-by-step explanation:
The question "How much Chakra do you need to pop a rubber ball?" merges fictional concepts with physical actions. Chakra, in this context, is likely referencing the energy used by ninjas in the anime Naruto for their special abilities, not a measurable physical force capable of interacting with objects like rubber balls. Therefore, a direct answer can't be provided in conventional terms.
To answer the spirit of the question, in the Naruto universe, the amount of Chakra needed to perform a task varies with the skill level of the ninja and the technique used. No specific measure of Chakra is described for mundane tasks such as popping a ball. If likened to physical energy, the amount of force needed to pop a rubber ball would be dependent on the thickness and material of the ball and could be measured in newtons (N) in physics.
If we were to humor the idea within the Naruto context, a ninja would simply apply enough Chakra infused touch or use a minor Chakra-based technique to exert the necessary force to pop the ball. But again, this is purely within the realm of the fictional world's mechanics. For a real-world application, understanding the physical properties of the rubber ball and applying enough pressure to exceed its tensile strength would be the way to go about popping it.