the room will either cool down or warm up the water until it is the same temperature as the room around it.
        
             
        
        
        
The element can also be called gold-197. It has Mass number
is 197, atomic number is 79 and electrons 79, Atoms that have the same number
of protons but different number of neutrons. Isotopes have identical numbers of
protons and electrons.
 
        
             
        
        
        
Answer:
D. The mixing of warm and cold water
Explanation:
 
        
             
        
        
        
Answer : The reaction is endothermic.
Explanation :
Formula used :

where,
 = change in temperature =
 = change in temperature = 
Q = heat involved in the dissolution of KCl = ?
m = mass = 0.500 + 50.0 = 50.5 g
c = specific heat of resulting solution = 
Now put all the given value in the above formula, we get:


The heat involved in the dissolution of KCl is positive that means as the change in temperature decreases then the reaction is endothermic and as the change in temperature increases then the reaction is exothermic.
Hence, the reaction is endothermic.