How to distinguish glycerin, acetic acid and formalin in bottles without labels,

How to distinguish glycerin, acetic acid and formalin in bottles without labels, a) by physical, b) by chemical properties? Write down the necessary equations of chemical reactions.

A) We distinguish by smell: glycerin does not smell, acetic acid has the smell of table vinegar, formalin has a sharp unpleasant smell.
B) We use freshly prepared copper hydroxide – a blue precipitate.
1.2СН3СООН + Сu (OH) 2 = (CH3COO) 2CU + H2O (blue solution)
2. Glycerin forms copper glycerate – blue solution.
3. Formalin is a solution of formic aldehyde, after adding CU (OH) 2 to it, heat the test tube – a bright orange precipitate falls out – copper hydroxide (1)
HCOH + 2 Сu (OH) 2 = HCOOH +2 CUOH + 2H2O