Name any two noble gases.

$(i)$ Name the scientist who discovered neutrons.
$(ii)$ State the charge and mass of a neutron.
$(iii)$ Where is a neutron located in an atom?

An ion $X^{2-}$ contains $10$ electrons and $8$ neutrons. What are the atomic number and mass number of element $X$?

Identify the isotopes out of $A, B, C$ and $D$ given the following representations:
${ }_{17}^{35} A, { }_{20}^{40} B, { }_{17}^{37} C, { }_{19}^{38} D$

State whether the following statement is true or false:
The relative atomic masses of all elements have been found with respect to an atom of oxygen-$16$.

Identify the $Mg^{2+}$ ion from the figures,where $n$ and $p$ represent the number of neutrons and protons,respectively.