<u>Answer:</u> The tree was burned 16846.4 years ago to make the ancient charcoal
<u>Explanation:</u>
The equation used to calculate rate constant from given half life for first order kinetics:

where,
 = half life of the reaction = 5715 years
Putting values in above equation, we get:

Rate law expression for first order kinetics is given by the equation:
![k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%5Clog%5Cfrac%7B%5BA_o%5D%7D%7B%5BA%5D%7D)
where,
k = rate constant  = 
t = time taken for decay process = ? yr
 = initial amount of the sample = 100 grams
[A] = amount left after decay process =  13 grams
Putting values in above equation, we get:

Hence, the tree was burned 16846.4 years ago to make the ancient charcoal
 
        
             
        
        
        
Answer:
              Mass = 0.158 g
Explanation:
Formula used,
P V = n R T
Or,
n = P V / R T
Putting values,
n = 0.948 atm . 0.025 L / 0.0821 L.atm.K⁻¹.mol⁻¹ . 291.45
n = 0.00099 mol
Note: we have changed pressure from mmHg to atm, volume from mL to L and temperature from C to K)
Also,
Mass = n . Molecular Mass
Mass = 0.00099 mol × 159.808 g/mol
Mass = 0.158 g
 
        
             
        
        
        
Answer:
The answer to your question is
1.- Volume = 3.4 ml
2.- Volume = 0.61 ml
3.- Mass = 2872.8 pounds
Explanation:
Problem 1
Volume = 18 ml
mass = 35.6 g
density = 10.5 g/ml
Process
1.- Calculate the volume of silver
Formula

solve for volume 

Substitution

<u>volume = 3.4 ml</u>
2.- Problem 2
Total volume = ?
Volume = 18 + 3.4 
Volume = 21.4 ml
Data
mass = 8.3 g
density = 13.6 g(ml
volume = ?
Formula 

Solve for volume

Substitution

Result 
<u>volume = 0.61 ml</u>
3.- Problem 3
Data
volume = 345 gal
density = 1 g/ml
mass = ?
Formula

Solve for mass
mass = density x volume
Covert gal to ml
                             1 gal --------------- 3785 ml
                          345 gal -------------  x
                             x = (345 x 3785) / 1
                             x = 1305825 ml
Substitution
mass = 1 x 1305825
mass = 1305825 g
Convert g to pounds
                         1 g ------------------- 0.0022 pounds
               1305825 g ----------------   x
                         x = (1305825 x 0.0022)
                        <u> x = 2872.8 pounds</u>
 
        
             
        
        
        
Answer:
ΔS° = - 47.2 J/mol.K
Explanation:
ΔS°= 4(S°mH3PO4) - 6(S°mH2O) - S°mP4O10
∴ S°mH2O(l) = 69.9 J/mol.K
∴ S°mP4O10 = 231 J/mol.K
∴ S°mH3PO4 = 150.8 J/mol.K
⇒ ΔS° = 4*(150.8) - 6*(69.9) - 231
⇒ ΔS° = - 47.2 J/mol.K