Identify a substance that is not in its standard state. refer to table b in appendix ii of the textbook to answer this question. identify a substance that is not in its standard state. refer to table b in appendix ii of the textbook to answer this question. ni(s) h2(g) o2(g) ba(s) co(s)

The phase of an element or a pure substance under standard conditions of temperature and pressure, 1 atm and is referred to as the standard state of that substance, at which the element will be stable.

Metals like Na, Li, K, Mg, Ca, Ni, Cu, Fe are all solids at standard conditions.

Bromine and mercury are liquids in their standard state.

Diatomic hydrogen, nitrogen, oxygen, chlorine, fluorine, and all noble gases are gases in their standard state.

Therefore, all the options are in the standard state except CO(s), carbon monoxide is a gas at room temperature.