Respuesta :
the reddish brown gas is NOX, now you just think the substance reacted with iron is nitrate salt of some metal X......hope you know the Metal X ,,,
Answer:
The mysterious substance is Nitrogen Dioxide
Explanation:
The mysterious substance is Nitrogen Dioxide in solid form. When heated it releases the reddish-brown gas that has a strong and pungent odor.
It is common to see this gas as a result of the combustion process carried out in thermal plants, especially when the material submitted to combustion is composed of oil or gases. This occurs a lot in many industrial processes and can be seen even in older motor vehicles.
It is important to protect yourself against this gas, because it can cause irritation of the eyes and nose, in addition to pulmonary emphysema, which can be very dangerous.