Thank you for reporting, we will resolve it shortly
Q.
The masses of neutron and proton are $1.0087$ and $1.0073$ amu respectively- If the neutrons and protons combine to form helium nucleus of mass $4.0015$ amu the binding energy of the helium nucleus will be
Mass defect, $\Delta \hat{m}=2\left(m_{n}+m_{p}\right)-m_{ He }$
$(\because$ helium nucleus has two protons and two neutrons)
$ \therefore \Delta m =2(1.0087+1.0073)-4.0015 $
$=4.032-4.0015=0.0305$
Binding energy,
$E_{B} =\Delta m \times 931 \,MeV $
$=0.0305 \times 931 $
$=28.4 \,MeV$