Alkenes must undergo addition because they have easily broken tt bonds. 
Markonikov's rule states in the addition of HX to an unsymmetrical alkene, the H atom bonds to the less substituted carbon atom.
 alkenes are unsaturated hydrocarbons because they have fewer than the maximum number of hydrogen atoms per carbon.
Alkyl halides have good leaving groups and therefore readily undergo substitution and elimination reactions. 
In hydroboration, the boron atom bonds to the substituted carbon.
Hydroxides, amines and alcoxides undergo substitution and elimination, but can do so only when the heteroatom is made into a good leaving group.
 
        
             
        
        
        
Answer:
2 moles 
Explanation:
Let us first start by calculating the molecular mass of Al₂O₃.
The mass of a mole of any compound is called it's molar mass. 1 molar mass 6.02 X 10²³, or Avogadro's number, of compound entities.
Say, 1 mole of Al₂O₃ has 6.02 X 10²³ of Al₂O₃ molecules/atoms. It also has 2*6.02 X 10²³ number of Al atoms and 3*6.02 X 10²³ number of O atoms.
Molecular mass of Al : 26.981539 u
Molecular mass of O: 15.999 u
Therefore, molecular mass of Al₂O₃ is:
= 
 u
= 101.960078 u
This can be approximated to 102 u.
1mole weighs 102 u
So, 2moles will weigh 2*102 = 204 u
 
        
                    
             
        
        
        
The answer to your question is,
Metalloids. They are a mix of elements that are both metals and non-metals in one.
-Mabel <3