We can use a simple equation to solve this problem.
 d = m/v
Where d is the density, m is the mass and v is the volume.
d = ?
m = 87.47 mg = 87.47 x 10⁻³ g
v = 0.03 mL
By applying the equation,
   d = 87.47 x 10⁻³ g
/ 0.03 mL
   d = 2.92 g/mL
Hence, the density of the mixture is 2.92 g/mL.
 
        
             
        
        
        
Answer:
A change is called irreversible if it cannot be changed back again. In an irreversible change, new materials are always formed.
Explanation:
 
        
                    
             
        
        
        
Answer:
Some chemical indicators perceived while a piece of paper is burning are:
Production of an Odor: there is a smell of burnt paper 
Change in Temperature:  combustion is a highly exothermic reaction , so the temperature increase
Change in Color: paper changes to ashes as the burning process occurs
 
        
             
        
        
        
Mass = moles x molar mass
so mass of 6 moles of h2 is: 6×1×2 = 12g