Answer:
4- radioactive isotopes
Explanation:
I don't remember exactly but this question was on the regents 
 
        
             
        
        
        
Answer:
Okay
Explanation:
The ingredients of photosynthesis are:
Carbon dioxide
Water
Light
Hope this helps <3
 
        
                    
             
        
        
        
Answer:
Heat flows from the block at high temperature to the one with lower temperature
Explanation:
The direction of heat flow is from a body at higher temperature to one with a lower temperature. 
- Temperature gradient determines the way and manner in which heat is dissipated. 
- As a system tend to increase entropy, it ensures that heat moves from hotter body to a colder body. 
- Heat movement here is by conduction as the body touches. 
- When both bodies reaches the same temperature, thermal equilibrium is established.