The answer is C because you don’t have to worry about the number in front of the decimal unless it is something greater than zero. A- Doesn’t have there sig figs. B- The zero after the 5 doesn’t change it. D- The three at the end doesn’t matter because it does not round it up.
        
                    
             
        
        
        
Boiling Water is a physical change. When water gets to a certain temperature, it's boiling point starts. 
        
                    
             
        
        
        
4I₂+9O₂= 2I₄+2O₉
Reactants: 8 iodine, 18 oxygen
Products: 8 iodine, 18 oxygen
Balanced!!
        
             
        
        
        
A weak bond between two molecules resulting from an electrostatic attraction between a proton in one molecule and an electronegative atom in another
        
                    
             
        
        
        
 when iron and oxygen the reactin form Fe2O3 balance equation for this is  <span>4Fe + 3O2---> 2Fe2O3 
9moles of O2 are needed to produce 6mol of Fe2O3 since the ratio of oxygen to iron(II)oxide is 3:2 
                               hope its help</span>