The valves stop the blood from flowing backwards
        
             
        
        
        
Hey there! 
Oxygen has a molar mass of 16. That means 16g of oxygen is 1 mole. 
32.6 ÷ 16 = 2.0375 moles 
We have 2.0375 moles. 
There are 6.022 x 10²³ atoms in one mole. 
2.0375 x 6.022 x 10²³ 
1.3 x 10²⁴ 
There are 1.3 x 10²⁴ atoms in 32.6 grams of oxygen. 
Hope this helps! 
 
        
                    
             
        
        
        
1.one substance must dissolve another : the solvent breaks the the solute causing it to dissociate into the solvent it can be both solids or gases that dissolve in the solute
2.the melting point will be higher than 100 degrees as the salt causes the solution to gain a higher melting point
3.either released or absorbed : energy is required to dissolve the solute but the solute may also release energy
4.the salt dissolved most quickly in the warm water : as there is more energy for the solute to dissolve 
hope that helps 
        
                    
             
        
        
        
Malleable, shiny and good conductors
A B E
        
             
        
        
        
Based off the salt levels in each water.