<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
Halogen are the most reactive due to their electronic configuration
<u>Answer:</u>
<em>When we finish, the temperature would be 32.5℃</em>
<em></em>
<u>Explanation:</u>
Density of water = mass/volume
So,
Mass of water = Density × Volume


where
= Final T - Initial T
Q is the heat energy in calories
c is the specific heat capacity (for water 1.0 cal/(g℃))
m is the mass of water
plugging in the values


Final T = ∆T + Initial T
= 7.5℃ + 25℃ = 32.5℃ (Answer).
It is B nevermind I thought it was c but it wasn't.
B ice melting hope it helps