If the nuclear force between two protons, two neutrons and between proton and neutron is denoted by `F_(p p), F_(n n)` and `F_(pn)` respectively, then

F_(pp),F_("nn")and F_(np) are the nuclear forces between proton - proton , neutron - neutron and neutron - proton respectively . Then relation between them is

Nuclear force between proton-proton is ______________.

In the nucleus of helium if F_1 is the net force between two protons, F_2 is the net force between two neutrons and F_3 is the net force between a proton and a neutron. Then,

Let F_(pp), F_(pn) and F_(nn) denote the magnitudes of the nuclear force by a proton on a proton, by a proton on a neutron and by a neutron on a neutron respectively. When the separation is 1 fm ,