On the bombardment of a neutron with Boron,an $\alpha$-particle is emitted. The product nucleus formed is:

If the ratio of the mass numbers of two nuclei is $27 : 125$, then the ratio of their surface areas is

The ratio of the nuclear radii of ${}^{135}Cs$ to ${}^{40}Ca$ is:

Which of the following particles are constituents of the nucleus?

Consider the following statements ($X$ and $Y$ stand for two different elements):
$(I)$ ${ }_{32}^{65} X$ and ${ }_{33}^{65} Y$ are isotopes.
$(II)$ ${ }_{42}^{86} X$ and ${ }_{42}^{85} Y$ are isotopes.
$(III)$ ${ }_{85}^{174} X$ and ${ }_{88}^{177} Y$ have the same number of neutrons.
$(IV)$ ${ }_{92}^{235} X$ and ${ }_{94}^{235} Y$ are isobars.
Which of the above statements are correct?

Which of the following pairs is an isobar?