Answer
A runner ran 20 miles in 150 minutes. If she runs at that ... run in 15 minutes? How fast is she running in miles per hour? What is her pace in minutes per mile?
Explanation:
 
        
                    
             
        
        
        
Answer:
Tin exists in two oxidation states, +4 and +2. Elemental tin is readily oxidized to the dipositive ion in acidic solution, but this Sn2+ ion is converted to the Sn4+ ion by many mild oxidizing agents, including elemental oxygen. Oxidation under alkaline conditions normally gives the tetrapositive (Sn4+) state.
 
        
             
        
        
        
Answer:
C4H6
Explanation:
See attached table
Convert each of the masses into moles by dividing the mass by the molar mass of that element.  That yields 3.83 moles of C and 6 moles of O.  I rounded up the C to 4 moles to result in an empirical formula of C4H6
 
        
             
        
        
        
Mass of solute = 25.8 g
mass solution = 212 g
% =(  mass of solute / mass solution ) x 100
% = ( 25.8 / 212 ) x 100
% = 0.122 x 100
= 12.2 %
        
                    
             
        
        
        
Answer: N = 2.78 × 10^23 atoms
There are N = 2.78 × 10^23 atoms in 70g of Au2cl6
Completed Question:
Calculate the number of gold atoms in a 70g sample of gold(III) chloride . Be sure your answer has a unit symbol if necessary, and round it to significant digits
Explanation:
Given:
Molar mass of Au2cl6 = 303.33g/mol
Mass of Au2cl6 = 70g
Number of moles of Au2cl6 = 70g/303.33g/mol = 0.231mol
According to the chemical formula of Au2cl6,
1 mole of Au2cl6 contains 2 moles of Au 
Number of moles of Au = 2 × 0.231mol = 0.462mole
There are 6.022 × 10^23 atoms in 1 mole of an element.
Number of Atom of gold in 0.462 mole of gold is:
N = 0.462 mol × 6.022 × 10^23 atoms/mol
N = 2.78 × 10^23 atoms