What is the packing fraction of $_{26}^{56}Fe$ (Isotopic mass $= 55.92066$)?

In the decay,${}_Z^AX \to {}_{6}^{12}C + {}_{+1}^{0}\beta$,identify the values of $A$ and $Z$.

Calculate the mass defect in the following nuclear reaction:
$_1H^2 + _1H^3 \to _2He^4 + _0n^1$
(Given: mass of $_1H^2 = 2.014 \ amu$,$_1H^3 = 3.016 \ amu$,$_2He^4 = 4.004 \ amu$,$_0n^1 = 1.008 \ amu$) (in $amu$)

Nuclei tend to have more neutrons than protons at high mass numbers because

In a nuclide, one $a.m.u.$ of mass is dissipated into energy to bind its nucleons. The energy equivalent of this mass is

$A$ nuclear reaction must be balanced in terms of