Answer: The constraints could be lack of materials, funds, or time. Another constraint could be size or shape.
Explanation:
E :)
 
        
                    
             
        
        
        
Answer:
Option B : burning of wood 
Explanation:
Chemical change is a change where a new substance is created like when you will bur wood you get ash this is a new substance, so burning of wood is a chemical change.
  
 
        
             
        
        
        
Answer:
78.85
Explanation:
To <u>calculate the average atomic mass of the isotopes </u>we use the <em>given masses and abundances</em>, as follows:
- Mass of Isotope 1 * Abundance of Isotope 1 + Mass of Isotope 2 * Abundance of Isotope 2 + ....
 
In other words:
- 78 amu * 75/100 + 81 amu * 15/100 + 82 amu * 10/100 = 78.85
 
So the answer is 78.85.
 
        
             
        
        
        
Answer: 1
Explanation: Lithium has a single electron in the second principal energy level, and so we say that lithium has one valence electron.