The compound Fe2O3 contains C) 5 total atoms. 
This is because there are 2 atoms of Fe (iron) and 3 atoms of O (oxygen) bonded together in this compound, as denoted by the subscripts, and 2+3 = 5.
Hope this helps!
        
                    
             
        
        
        
Answer: Rate law=![k[A]^1[B]^2](https://tex.z-dn.net/?f=k%5BA%5D%5E1%5BB%5D%5E2) , order with respect to A is 1, order with respect to B is 2 and total order is 3. Rate law constant is
, order with respect to A is 1, order with respect to B is 2 and total order is 3. Rate law constant is 
Explanation: Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.
![Rate=k[A]^x[B]^y](https://tex.z-dn.net/?f=Rate%3Dk%5BA%5D%5Ex%5BB%5D%5Ey)
k= rate constant
x = order with respect to A
y = order with respect to A
n = x+y = Total order
a) From trial 1: ![1.2\times 10^{-2}=k[0.10]^x[0.20]^y](https://tex.z-dn.net/?f=1.2%5Ctimes%2010%5E%7B-2%7D%3Dk%5B0.10%5D%5Ex%5B0.20%5D%5Ey) (1)
    (1)
From trial 2: ![4.8\times 10^{-2}=k[0.10]^x[0.40]^y](https://tex.z-dn.net/?f=4.8%5Ctimes%2010%5E%7B-2%7D%3Dk%5B0.10%5D%5Ex%5B0.40%5D%5Ey) (2)
    (2)
Dividing 2 by 1 :![\frac{4.8\times 10^{-2}}{1.2\times 10^{-2}}=\frac{k[0.10]^x[0.40]^y}{k[0.10]^x[0.20]^y}](https://tex.z-dn.net/?f=%5Cfrac%7B4.8%5Ctimes%2010%5E%7B-2%7D%7D%7B1.2%5Ctimes%2010%5E%7B-2%7D%7D%3D%5Cfrac%7Bk%5B0.10%5D%5Ex%5B0.40%5D%5Ey%7D%7Bk%5B0.10%5D%5Ex%5B0.20%5D%5Ey%7D)
 therefore y=2.
 therefore y=2.
b) From trial 2: ![4.8\times 10^{-2}=k[0.10]^x[0.40]^y](https://tex.z-dn.net/?f=4.8%5Ctimes%2010%5E%7B-2%7D%3Dk%5B0.10%5D%5Ex%5B0.40%5D%5Ey) (3)
    (3)
 From trial 3: ![9.6\times 10^{-2}=k[0.20]^x[0.40]^y](https://tex.z-dn.net/?f=9.6%5Ctimes%2010%5E%7B-2%7D%3Dk%5B0.20%5D%5Ex%5B0.40%5D%5Ey) (4)
   (4)
Dividing 4 by 3:![\frac{9.6\times 10^{-2}}{4.8\times 10^{-2}}=\frac{k[0.20]^x[0.40]^y}{k[0.10]^x[0.40]^y}](https://tex.z-dn.net/?f=%5Cfrac%7B9.6%5Ctimes%2010%5E%7B-2%7D%7D%7B4.8%5Ctimes%2010%5E%7B-2%7D%7D%3D%5Cfrac%7Bk%5B0.20%5D%5Ex%5B0.40%5D%5Ey%7D%7Bk%5B0.10%5D%5Ex%5B0.40%5D%5Ey%7D)
 , x=1
, x=1
Thus rate law is ![Rate=k[A]^1[B]^2](https://tex.z-dn.net/?f=Rate%3Dk%5BA%5D%5E1%5BB%5D%5E2)
Thus order with respect to A is 1 , order with respect to B is 2 and total order is 1+2=3.
c) For calculating k:
Using trial 1:  ![1.2\times 10^{-2}=k[0.10]^1[0.20]^2](https://tex.z-dn.net/?f=1.2%5Ctimes%2010%5E%7B-2%7D%3Dk%5B0.10%5D%5E1%5B0.20%5D%5E2)
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Volume fraction = volume of the element / volume of the alloy
Volume = density * mass
Base: 100 grams of alloy
mass of tin = 15 grams
mass of lead = 85 grams
volume = mass / density
Volume of tin = 15g / 7.29 g/cm^3 = 2.06 cm^3
Volume of lead = 85 g / 11.27 g/cm^3 = 7.54 cm^3
Volume fraction of tin = 2.06 cm^3 / (2.06 cm^3 + 7.54 cm^3) = 0.215
Volume fraction of lead = 7.54 cm^3 / (2.06 cm^3 + 7.54 cm^3) = 0.785 
As you can verify the sum of the two volume fractions equals 1: 0.215 + 0.785 = 1.000
        
             
        
        
        
Answer:
Moment=Force x Pivot
Explanation:
A moment is the turning effect of a force. Moments act about a point in a clockwise or anticlockwise direction.
Law of moments:
When an object is balanced (in equilibrium) the sum of the clockwise moments is equal to the sum of the anticlockwise moments.
How to calculate moments:
Moment=Force x Pivot