Which research question on World War 2 is too narrow?

who was president of the united states at the start of World War II

Is the answer

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Explanation:

Percentage of mass converted to energy = 99.9 %

Explanation:

By far most of the solar system's mass is in the Sun itself: somewhere between 99.8 and 99.9 percent. The rest is split between the planets and their satellites, and the comets and asteroids and the dust and gas surrounding our star. Seen from afar (on the scale of distances between stars) the presence of the solar system would not be obvious. We would simply see a normal-looking star. Perhaps we would pick up the presence of Jupiter, which makes up two thirds or so of the solar system outside of the Sun, by mass.