Final answer:
In the decay mode η⁰→γ+γ, the eta-zero meson decays into two photons, which are gamma rays. The conservation of energy and quantum numbers is respected in the decay process.
Step-by-step explanation:
The decay of the eta-zero meson (η⁰) into two photons is represented by the equation η⁰→γ+γ. The particles present in the final state of this decay mode are photons, specifically gamma rays. It's important to note that this decay process involves the strong interaction, and the quark content of the eta-zero meson changes into energy that is carried away by the two photons. This process is an example of particle decay where the conservation of energy and various quantum numbers are maintained.