What reaction model represents a nuclear fission reaction

Explanation:

When a neutron hits the nucleus of a heavy atom, the nucleus splits into two fragments of roughly equal mass and emits two or three neutrons.

A model that fits the process is

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

1. a)c-14 has two more protons

2. d)they have different numbers of protons, neutrons, and valence electrons; they are all gases at room temperature.

3. c) iron and nickel.