Mg3N2 is Magnesium nitride
        
             
        
        
        
Hey there!
Label A: Sublimation
Label B: Condensation
Label C: Melting
Remember sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. Condensation is the conversion of a vapor or gas to a liquid. Melting is becoming liquefied by heat.
Hope this helps!
        
             
        
        
        
None of the above? 
(Is there any statements?)
        
             
        
        
        
The molar mass of CO2 can be calculated as follows; 
CO2 — 12 + (16x2) = 12+ 32 = 44 g
Therefore molar mass of CO2 is 44 g/mol
In 44 g of CO2 there’s 1 mol of CO2
Then 1 g of CO2 there’s 1/44 mol of CO2
Therefore in 78.3 g of CO2 there’s — 1/44 x 78.3 =1.78 mol of CO2