Since the chemical definition of "stable" means close to having a full valence shell, the answer is 3d^10.
The answer is state.
That is the state would be least helpful in determining whether a substance is a metal or a nonmetal. The state can only tells that a compound is liquid, gas or solid. But it can't tell whether a substance is metal or non-metal. So it is the least helpful in determining whether a compound is metal or non-metal.
DNA and RNA is your answer
