An atom that has 13  protons and 15  neutrons  is isotope  of Aluminium (answer C)
 <u><em>Explanation</em></u>
- Isotope  is a form of the same element with   the equal number of protons but difference number  of neutrons  in  their nuclei.
- In other words isotope has the same  atomic number but different mass  number.
- Atomic  number of a element is determined by number of  protons of an element.
- from the  periodic table   Aluminum  in atomic number 13 therefore  it has 13 protons  <em>therefore an atom that  has 13  protons and 15 neutrons is   a isotope  of Aluminium. </em>
 
        
                    
             
        
        
        
The will not affect the wind. When it is windy the wind turns a turbine. Once the wind has gone through the turbine it is just normal wind, none of the wind is lost when this happened
        
                    
             
        
        
        
Answer: 1 mole ➡️ 6.022×10²³ atoms of si.
X mole ➡️ 2.8×10²⁴ atoms of si.
X = 2.8×10×10²³/6.022×10²³
= 28/6.022
= 4.65 moles.
Explanation:
 
        
             
        
        
        
Answer:
c : 13%
Explanation:
Data Give:
Experimental density of vanadium = 6.9 g/cm³ 
percent error = ?
Solution:
Formula used to calculate % error
   % error = [experimental value -accepted value/accepted value] x 100
The reported accepted density value for vanadium = 6.11 g/cm³
Put value in the above equation
                   % error = [ 6.9 - 6.11 / 6.11 ] x 100
                   % error = [ 0.79 / 6.11 ] x 100
                   % error = [ 0.129] x 100
                   % error = 12.9
Round to the 2 significant figure
% error = 13 %
So, option c is correct