Can you determine the contents of the unlabeled jar through observation alone?

This question appears incomplete but generally the answer is NO

Explanation:

Observation of the contents of an unlabeled jar depends solely on some of the physical properties of the content which is not good enough when identifying the contents of an unlabeled jar. This is because several substances have the same physical properties. For example, water and several acidic solutions appear the same in terms of colour and viscosity. Hence, a jar of water and a jar of hydrochloric acid cannot be differentiated by mere observation but with the use of litmus paper.

And a solution of hydrochloric acid and sulphuric acid cannot be differentiated by observation alone except a jar ammonia is brought close to the two jars (the one with hydrochloric acid will form a white fume with ammonia); hence relying on the chemical properties of both substances.

NOTE: Observation is done through sight, smell, feel, sound and taste without relying on another procedure/analysis to determine them.

dynamic equilibrium is the answer.