<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:
dipole-dipole
Explanation:
Intermolecular forces exists between the molecules of a substance in a particular state of matter.
The type of intermolecular forces present in a substance is determined by the electronegativity difference between the atoms that compose the substance.
There is a non zero electronegativity difference between Br and F hence the molecule is polar and the intermolecular forces between the molecules of BrF are dipole-dipole forces.
C7H16, where C=12.01, and H=1.01, so the weight of the molecule would be 7(12.01)+16(1.01), or 100.23. The percentage of carbon would be found by ((7*12.01)/100.23)*100=83.88% Carbon
((16*1.01)/100.23)*100=16.12% Hydrogen
Answer:
If the volume is doubled and the number of molecules is doubled, pressure is unchanged
Explanation:
Step 1: Data given
Temperature = constant
Volume will be doubled
Number of molecules will be doubles
Step 2:
p*V = n*R*T
⇒ gas constant and temperature are constant
Initial pressure = n*R*T / V
Initial pressure = 2*R*T/2
Initial pressure = RT
Final pressure = 4*RT / 4
Final pressure = R*T
If the volume is doubled and the number of molecules is doubled, pressure is unchanged