The radius of an atom is of the order of

The nucleus of an atom can be assumed to be spherical. The radius of the nucleus of mass number $A$ is given by $1.25 \times 10^{-13} \times A^{1/3} \ cm$. The radius of the atom is $1 \ \mathring{A}$. If the mass number is $64$,then the fraction of the atomic volume that is occupied by the nucleus is:

Proton is

Which of the following particles is represented by the symbol $\alpha$?

Which particle leaves no track in a Wilson cloud chamber?

Match the following:

$A$. Chadwick	$1$. Cathode rays
$B$. Rutherford	$2$. $X$-ray spectra
$C$. Moseley	$3$. Discovery of neutrons
$D$. $J$. $J$. Thomson	$4$. Nuclear atom model