Answer:
Their densities are different as well
Explanation:
Density is worked out by dividing mass by volume. If the mass was the same then the densities would be as well. But it's not.
How many marks is this question?
The mass of a neutron is:

Since we know its speed, we can calculate the neutron's momentum:

The problem says the photon has the same momentum of the neutron, p. The photon momentum is given by

where h is the Planck constant, and

is the photon wavelength. If we re-arrange the equation and we use the momentum we found before, we can calculate the photon's wavelength:

And since we know the photon travels at speed of light c, we can now calculate the photon frequency:
The energy required to start a reaction IS called the activation energy. TRUE