On the bombardment of a neutron with Boron,an $\alpha$-particle is emitted. The product nucleus formed is:

It is now believed that protons and neutrons (which constitute nuclei of ordinary matter) are themselves built out of more elementary units called quarks. $A$ proton and a neutron consist of three quarks each. Two types of quarks,the so-called 'up' quark (denoted by $u$) of charge $+(2/3)e$,and the 'down' quark (denoted by $d$) of charge $-(1/3)e$ together with electrons build up ordinary matter. Suggest a possible quark composition of a proton and neutron.

Give one example each of central force and non-central force.

In the following nuclear reaction $_{12}Mg^{24} + _{2}He^{4} \to _{14}Si^{X} + _{0}n^{1}$,the value of $X$ is:

Out of gravitational,electromagnetic,Van der Waals,electrostatic,and nuclear forces,which two are able to provide an attractive force between two neutrons?

Given the mass of an iron nucleus as $55.85 \, u$ and $A=56$,find the nuclear density.