State whether the following statement is true or false:
Atoms combine in the ratio of small whole numbers to form compounds.

Rutherford's $\alpha-$ particle scattering experiment showed that
$(i)$ Electrons have negative charge
$(ii)$ The mass and positive charge of the atom is concentrated in the nucleus
$(iii)$ Neutron exists in the nucleus
$(iv)$ Most of the space in atom is empty
Which of the above statements are correct?

Calculate the number of neutrons present in the nucleus of an element $X$ which is represented as $^{31}_{15}X$.

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-$16$.

Answer the following in one line or one word:
$(a)$ Who discovered the neutron?
$(b)$ On the basis of Thomson's model of an atom,explain how the atom is neutral as a whole.
$(c)$ What is the maximum number of electrons that can be accommodated in the outermost shell of an atom?
$(d)$ What term is assigned to the atoms of different elements having the same atomic mass but different atomic numbers?
$(e)$ How many neutrons are present in a hydrogen atom?

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