Answer:
5.17 × 10^-1
Explanation:
move the decimal to the right one space.
when you move the decimal to the right its exponent becomes a negative.
 
        
             
        
        
        
1.51 x 10²⁵atoms
Explanation:
Given parameters: 
Mass of Na = 578g 
Unknown: 
Number of atoms = ? 
Solution: 
  To find the number of atoms, we must first find the number of moles the given mass contains. 
   Number of moles  = 
    molar mass of Na = 23g 
  Number of moles =  
 =  25.13moles
 
    1 mole of a substance = 6.02 x 10²³atoms
     25.13 mole of Na = 25.13 x  6.02 x 10²³atoms 
  This gives  1.51 x 10²⁵atoms of Na
Learn more: 
Avogadro's constant brainly.com/question/2746374
#learnwithBrainly
 
        
             
        
        
        
Answer:
Phenolphthalein is an acid indicator, which means when we add water (pH 7) to it, it ionizes giving a pink color. We all know acid gives in solution. When we add phenolphthalein to acid due to the common ion effect concentration increases. turned the solution pink.
Explanation:
 
        
             
        
        
        
Answer:
200 W
Explanation:
Formula of Power is 
P= W/T
where 
W= Work and T= Time
so
4000/20 = 200J/s or 200 W