The Attractive Force Between Protons and Neutrons in the Nucleus

Multiple Choice

The attractive force between protons and neutrons in the nucleus is brought about by the exchange of a virtual pi-meson (mπ = 140 MeV/c²) . Estimate the longest time a virtual π⁰ can exist, in accordance with the uncertainty principle . (1 eV = 1.6 × 10−¹⁹ J.)

A) 2.4 × 10−²⁴ s
B) 6.9 × 10−²⁷ s
C) 3.3 × 10−¹⁸ s
D) 2.4 × 10−²¹ s
E) 1.6 × 10−¹⁹ s