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

Is it possible for the atom of an element to have one electron,one proton,and no neutron? If so,name the element.

Write the conclusions drawn by Rutherford for the following observations during his $\alpha$-scattering experiment:
$(a)$ Most of the alpha particles passed straight through the gold foil.
$(b)$ Some alpha particles got deflected from their path.
$(c)$ $A$ very small fraction of alpha particles got deflected by $180^{\circ}$.

An atom with atomic number $9$ and mass number $19$ will have the following constituents:

State three features of the nuclear model of an atom put forward by Rutherford.

Give one point of similarity and one point of difference between isotopes of ${ }_{6}^{14} C$ and ${ }_{6}^{12} C$.