Two nuclei which are not identical but have the same number of nucleons represent

Which of the following sets of nuclei represents a triad of isotones?

Which of the following is not correct?

The triad of nuclei that is isotonic is

$_6C^{11}$ and $_5B^{11}$ are referred to as:

$_{35}X^{88}$ is an unstable isotope,which decays in two successive steps to produce the stable isotope $_{32}Z^{84}$ as $_{35}X^{88}$ $\xrightarrow{I} Y$ $\xrightarrow{II} _{32}Z^{84}$. The correct statement is (possible emissions are $\alpha, \beta^-$,positron,neutron,and $_1H^1$,and in each step only one particle is involved).