Answer:
Extraction of aluminium
Aluminium ore is called bauxite . The bauxite is purified to produce aluminium oxide, a white powder from which aluminium can be extracted. The extraction is done by electrolysis. The ions in the aluminium oxide must be free to move so that electricity can pass through it.
 
        
                    
             
        
        
        
Answer:
A. In a graduated cylinder, put some quantity of water and measure the initial volume. Then put a coin and measure the volume. To find the volume of the coin, simply subtract the initial volume (water only) from the ending volume (water + coin). To measure the mass, take a dry coin and place it on an electronic scale. Density = mass / volume, so divide the mass by the volume to calculate the density of the coin. 
B. When measuring the volume, make sure to look at the graduated cylinder at eye level and read from the bottom of the meniscus.
 
        
             
        
        
        
Answer:
the answer for this question is the option D 
 
        
             
        
        
        
Noble gases
also known as Inert gases
        
             
        
        
        
Bohr model is valid only for hydrogen and hydrogen-like species, but quantum mechanical model can explain all elements....