Write any two observations which support the fact that atoms are divisible.

Complete the table on the basis of information available in the symbols given below:
$(a)$ ${ }_{17}^{35} Cl$
$(b)$ ${ }_{6}^{12} C$
$(c)$ ${ }_{35}^{81} Br$

Element	$n_{(p)}$	$n_{(n)}$

In the Thomson's model of atom,which of the following statements are correct?
$(i)$ The mass of the atom is assumed to be uniformly distributed over the atom.
$(ii)$ The positive charge is assumed to be uniformly distributed over the atom.
$(iii)$ The electrons are uniformly distributed in the positively charged sphere.
$(iv)$ The electrons attract each other to stabilize the atom.

$A$ helium atom has $2$ electrons in its valence shell,but its valency is not $2$. Explain.

State whether the following statement is true or false:
Each isotope of an element is an impure substance.

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