Original sentence: Pure osmium tetraoxide is probably colourless and it has been suggested that its yellow hue is due to osmium dioxide (OsO2)impurities although osmium (IV) oxide normally exists as a black powder so this may not be true
Edited sentence: Pure osmium tetraoxide is probably colourless and it has been suggested that its yellow hue is due to osmium dioxide (OsO2)impurities although osmium (IV) oxide normally exists as a black powder so this seems unlikely