So calculate the H for the other two reactions a room temperature and combine the reactions to calculate the H of the decomposition of calcium carbonate using the Hess's Law
        
             
        
        
        
Answer:
fijhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
Explanation:
 
        
             
        
        
        
Answer:
B
Explanation:
the group number is=valence electrons. element 1 is in group 1 element 18 is in group 8. 1<8
 
        
                    
             
        
        
        
Answer:
A- Physical, B- Chemical, C- chemical, D- Physical 
Explanation:
A is physical because you can see it changing its form is changing.
B is Chemical because a new substance is formed creating the orange color of rust.
C is a Chemical reaction because it is being broken down so the banana itself is changing not just how we see it. 
D is physical because we are just changing the shape/ size of the item, not anything to do with its substances.
 
        
                    
             
        
        
        
Answer:
41.9 g
Explanation:
We can calculate the heat released by the water and the heat absorbed by the steel rod using the following expression.
Q = c × m × ΔT
where,
c: specific heat capacity
m: mass
ΔT: change in temperature
If we consider the density of water is 1.00 g/mol, the mass of water is 125 g.
According to the law of conservation of energy, the sum of the heat released by the water (Qw) and the heat absorbed by the steel (Qs) is zero.
Qw + Qs = 0
Qw = -Qs
cw × mw × ΔTw = -cs × ms × ΔTs
(4.18 J/g.°C) × 125 g × (21.30°C-22.00°C) = -(0.452J/g.°C) × ms × (21.30°C-2.00°C)
ms = 41.9 g