Let $X$ be the adjacency matrix of a graph $G$ with no self loops. The entries along the principal diagonal of $X$ are
Answer : all Zeros
It is not said that how many node should be there in graph take a graph with single node And it is also mentioned that there is no loop .
Consider 5X5 matrix, for 1,1 for 2,2, since there is no self loop so all diagonal will be 0