Question

what is the density of neutrons ?

Answer 1

density of neutron is 2.3×1017 kg/m3. 

Answer 2

Neutrons stars are extreme objects that measure between 10 and 20 km across. They have densities of 1017 kg/m3(the Earth has a density of around 5×103 kg/m3 and even white dwarfs have densities over a million times less) meaning that a teaspoon of neutron star material would weigh around a billion tonnes.