Answer:
hi!
Explanation:
Well, some things I would do is to know the Periodic Table font and back. Know they elements and their class and atomic number and weight. Know how many atoms make up each element and how many protons, neutrons, and elements are in each atom. 
 
        
             
        
        
        
It is softer than topaz and and it is softer than diamond (diamond has a Mohs hardness of 10, which is the highest value of the scale) 
        
                    
             
        
        
        
Answer:
Part A 
  The volume of the gaseous product  is   
 
Part B 
 The volume of the the engine’s gaseous exhaust is   
 
Explanation:
Part A
From the question we are told that 
     The temperature is  
      The pressure is  
      The of  
The chemical equation for this combustion is 
                
  The number of moles of   that reacted is mathematically represented as
 that reacted is mathematically represented as 
                
The molar mass of   is constant value which is
 is constant value which is
                    
  
So          
              
The gaseous product in the reaction is  and water vapour
 and water vapour 
Now from the reaction 
     2 moles of  will react with 25 moles of
  will react with 25 moles of  to give (16 + 18) moles of
 to give (16 + 18) moles of  and
 and  
So
     1 mole of  will  react with 12.5 moles of
 will  react with 12.5 moles of   to give 17 moles of
 to give 17 moles of  and
 and  
This implies that 
     0.8754 moles of  will react with (12.5 * 0.8754 ) moles of
 will react with (12.5 * 0.8754 ) moles of  to give  (17 * 0.8754) of
 to give  (17 * 0.8754) of  and
 and  
So the no of moles of gaseous product is 
          
          
From the ideal gas law 
        
making V the subject 
         
Where R is the gas constant with a value 
 Substituting values 
            
 
            
 
Part B
From the reaction the number of moles of oxygen that reacted is 
          
          
The volume is 
       
       
No this volume is the 21% oxygen that reacted the 79% of air that did not react are the engine gaseous exhaust and this can be mathematically evaluated as
          
Substituting values 
         
 
         
 
 
        
             
        
        
        
Answer:
P.E for the 4kg bowling ball held 2.5 meters above head is 100j, while the other is 60j so the 4kg ball has more potential energy
 
        
             
        
        
        
<span>the one that is not a factor that contribute to natural selection is : Population stability
population refer to the capability of a community to maintain its total amount of organisms within a specific period of time.
This has nothing to do with natural selection, which basically a nature's way to reduce the number of organism to findout which organisms are more adaptive</span>