Given the mass of iron nucleus as `55.85u and A = 56, ` the nuclear density is
`(u = 1.66 xx 10 ^(-27) kg, r = 1.2 xx 10 ^(-15)m )`

Explanation

`m_(Fe)=55.85, 1u=1.66xx10^(-27)kg`
The density of matter in neutron stars (an astrophysical object) is comparable to this density. This shows that matter in these objects has been compressed to such an extent that they resemble a big nucleus.
`"nuclear density"=("mass of nucleus")/("volume of nucleus")`
`=(Axx1u)/((4)/(3)piR^(3))=(Axx1u)/((4)/(3)pi(R_(0)A^(1//3))^(3))`
`=(55.85xx1.66xx10^(-27))/((4pi)/(3)xx(1.2xx10^(-15))^(3))xx(1)/(56)=2.29xx10^(17)kgm^(-3)`