Rutherford's alpha-particle scattering experiment was responsible for the discovery of

Complete the following table.

Atomic Number	Mass Number	Number of Neutrons	Number of Protons	Number of Electrons	Name of the Atomic Species
$9$	-	$10$	-	-	-
$16$	$32$	-	-	-	sulphur
-	$24$	-	$12$	-	-
-	$2$	-	$1$	-	-
-	$1$	$0$	$1$	$0$	-

Composition of the nuclei of two atomic species $X$ and $Y$ are given as under:

	$X$	$Y$
Protons $=$	$6$	$6$
Neutrons $=$	$6$	$8$

Give the mass numbers of $X$ and $Y$. What is the relation between the two species?

If bromine atom is available in the form of,say,two isotopes $_{35}^{79}Br$ $(49.7 \%)$ and $_{35}^{81}Br$ $(50.3 \%),$ calculate the average atomic mass of bromine atom. (in $,u$)

Compare the properties of electrons,protons,and neutrons.

On the basis of Thomson's model of an atom,explain how the atom is neutral as a whole.