The charge topology in the fragmentation of $^{10}$C nuclei in a track nuclear emulsion at an energy of 1.2 GeV per nucleon is studied. In the coherent dissociation of $^{10}$C nuclei, about 82% of events are associated with the channel $^{10}$C $rig
htarrow$ 2$alpha +$ 2emph{p}. The angular distributions and correlations of product fragments are presented for this channel. It is found that among $^{10}$C $rightarrow$ 2$alpha +$ 2emph{p} events, about 30% are associated with the process in which dissociation through the ground state of the unstable $^9$Be$_{g.s.}$ nucleus is followed by $^8$Be$_{g.s.} +$ emph{p} decays.
The dissociation features in nuclear track emulsion of $^9$Be, $^{9,10}$C, and $^{12}$N nuclei of 1.2 A GeV energy are presented. The data presented for the nucleus $^9$Be can be considered as evidence that there is a core in its structure in the for
m of 0$^+$ and 2$^+$ states of the $^8$Be nucleus having roughly equal weights. Events of coherent dissociation $^9$C$rightarrow 3^3$He associated with the rearrangement of the nucleons outside the $alpha$-clustering are identified. A pattern of the charge fragment topology in the dissociation of $^{10}$C and $^{12}$N nuclei is obtained for the first time. Contribution of the unbound nucleus decays to the cascade process $^{10}$C$rightarrow ^9$B$rightarrow ^8$Be is identified.
