Adding a Tollens reagent to this type of compound will leave a silver mirror coating on the flask.  
Along with reducing sugars, they are detected by Fehling's test. They can be produced by adding a mild reducing agent to an acid chloride, through a Rosenmund reduction, or by the oxidation of a primary alcohol. Adding a Tollens reagent to this type of compound will leave a silver mirror coating on the flask.  The lightest one is used in making Bakelite and in preserving specimens. Given names ending in the suffix -al, FTP, name these compounds that have a hydrogen bonded to their carbonyl group, unlike ketones.
Along with reducing sugars, they are detected by Fehling's test.
aldehydes