Which of the following exists as a gas at 287K?

Formaldehyde (Methanal) Acetaldehyde (Ethanal) Propanal Acetone

Formaldehyde (Methanal)

Methanal exists as foul-smelling gas at room temperature. Ethanal is a volatile liquid which boils at 294K. Other aldehydes and ketones exist as either liquids or solids at room temperature.