I would say that the answer is d?
        
             
        
        
        
Silicon is the second most abundant element in the Earth´s crust and makes up around 27% of it.
 
        
             
        
        
        
Scientists use special tools to do their work. They gather data, or information, as they seek to learn about the world. In order to solve problems they must record data that is accurate and organized. This is an important part of the scientific method.
        
                    
             
        
        
        
Answer:
1. CO₂ → C + O₂
2. Fe₂ + O₂ → 2FeO
3. 2Al + 3CuO→  Al₂O₃  +  3Cu
Explanation:
1. 1 mol of CO₂ decomposes to 1 mol of C and 1 mol of oxygem
2. 1 mol of Fe₂ reacts with 1 mol of oxygen to produce 2 moles of iron (II) oxide
3. 2 moles of Al, reacts with 3 moles of cupper(II) oxide to produce 1 mol of aluminum dioxide and 3 moles of cupper