It might be the fourth one? Sorry, it’s been a while since I’ve done something like this.
        
                    
             
        
        
        
Answer:
X2Z3
Explanation:
Based on the clues, X is a metal and Z is a non-metal.
X could be aluminum and Z would need to be an element from the oxygen family. 
 
        
             
        
        
        
Answer: 66.66 ml
Explanation: Using Molarity equation:
 (stock solution)=
 (stock solution)= (solution to be prepared)
(solution to be prepared)
given: 



 (stock solution)=
 (stock solution)= (solution)
 (solution)
