Escribir ⇢ Escrito
El detective llegó al hotel con el número de la habitación escrito en un papel. El hotel estaba en una calle muy adjetive (transitada).
[tex] \boxed{ \bold{Explanation}}[/tex]
Remember that the impersonal forms are those that do not coincide in gender and number with the subject that performs the action.
Remember that the participle is a verbal form while an adjective always describes a quality of the noun, always agreeing in gender and number with the noun it accompanies.