The correct answers are 
-formation of a precipitate 
-bubble formation
-color change
-temperature change 
-odor formation
The only one that isn’t correct is change in state of matter. A change in a state of matter does not mean it’s a chemical change. For example, water boiling so it turns into gas is not a chemical change, and is a physical one. Also, water can freeze and turn into ice, which is also still a physical change. If something changes state of matter, it does not necessarily mean it’s a chemical change.
        
             
        
        
        
3Zn + 8HNO3 ---> 3Zn(NO3)2 + 4H2O + 2NO IF IT IS COLD AND DILUT NITRIC ACID .
IF IT IS HOT AND CONCENTRATED THEN:
Zn+ 4HNO3 ---> Zn(NO3)2 +2H2O +2NO2
        
             
        
        
        
A. ca is the answer because its short for carbon
        
                    
             
        
        
        
2 boxes of A 
Because C = A + B 
2 of A = 20 grams 
at the other hand we have 2 of B = 10 
So 20 + 10 = 30 grams