One electron is present in the outermost shell of the atom of an element $X$. What would be the nature and value of charge on the ion formed if this electron is removed from the outermost shell?

State reasons for the following statements:
$(i)$ Some elements possess fractional atomic mass.
$(ii)$ Isotopes of an element have similar chemical properties.
$(iii)$ Noble gases are inert.

Dalton's atomic theory successfully explained which of the following laws?
$(i)$ Law of conservation of mass
$(ii)$ Law of constant composition
$(iii)$ Law of radioactivity
$(iv)$ Law of multiple proportion

Dalton's atomic theory successfully explained:
$(i)$ Law of conservation of mass
$(ii)$ Law of constant composition
$(iii)$ Law of radioactivity
$(iv)$ Law of multiple proportions

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 $180^{\circ}$.

$(a)$ How many neutrons are present in $C-14$ isotope of carbon?
$(b)$ How many protons does $He^{2+}$ ion possess?
$(c)$ How many maximum electrons can be filled in the $3^{rd}$ orbit of an atom?
$(d)$ How many electrons does $He^{2+}$ ion possess?