They form molecules which can be in solution form if diluted in water, but some do form solutions on exposure to the atmosphere i.e they are deliquescent like pellets of sodium hydroxide
        
             
        
        
        
 Group 8 elements. They are unreactive and stable
        
             
        
        
        
Answer:
This is most likely a multi-stepped reaction. 
Explanation:
From the collision theory, we know that it is super improbable for 3 different molecules (2 NO and 1 O2) to all hit each other at the perfect speed in the perfect position to make the products. From this, we can pretty confidently say that this is most likely a multi-stepped reaction. 
Hope this helps! :)