Radius of $_2H{e^4}$ nucleus is $3 \,Fermi.$ The radius of $_{82}P{b^{206}}$ nucleus will be..........$fermi$
$5$
$6$
$11.16$
$8 $
The mass of an $\alpha$-particle is
Antiparticle of electron is
The increasing order of atomic radii of the following Group $13$ elements is
Which of the following pairs is an isobar
$\pi $ mesons can be