the correct answer: 2Ca3(PO4)2 + 6SiO2 -> P4O10 + 6CaSiO3
 
        
             
        
        
        
Answer:
Replacing the powdered lead oxide with large crystals
Explanation:
The large crystals have less surface area exposed to the other reagents than the powdered  lead oxide. High surface area leads to a high rate of reaction thus the products are formed faster, while a low surface area leads to a lower rate of reaction since the reagent is less exposed to the other reagents.
 
        
                    
             
        
        
        
Answer:
It's the 4th one. The car is accelerating gradually. 
 
        
             
        
        
        
Answer:
because the bones in the arm often pivot just like a lever does.
 
        
                    
             
        
        
        
The initial temperature is 137.34 °C.
<u>Explanation:</u>
As the specific heat formula says that the heat energy required is directly proportional to the mass and change in temperature of the system. 
Q = mcΔT
So, here the mass m is given as 23 kg, the specific heat of steel is given as c = 490 J/kg°C and the initial temperature is required to find with the final temperature being 140 °C. Also the heat energy required is 30,000 J.
ΔT =
ΔT =
Since the difference in temperature is 2.66, then the initial temperature will be
Final temperature - Initial temperature = Change in temperature
140-Initial temperature = 2.66
Initial temperature = 140-2.66 = 137.34 °C
Thus, the initial temperature is 137.34 °C.