Write two differences between isobars and isotopes.

Give a brief account of the development of the presently accepted model of the atom with the contributions made by different scientists. Write two features of this atomic model.

In response to a question,a student stated that in an atom,the number of protons is greater than the number of neutrons,which in turn is greater than the number of electrons. Do you agree with the statement? Justify your answer.

The number of valence electrons in $Cl^{-}$ ion are

Why do we need to calculate the average atomic mass of isotopes of an element for computation?

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?