Answer:
4
Step-by-step explanation:
Given that I no not see any explanation in the previos answer, I think you can benefit of this.
Exothermic refers only to the fact that the reaction releases energy in the form of heat when occurs. So, the enthalpy is higher at start and lower and the end.
Seen in this way, you can deduct that the change in enthalpy is negative, which is what the third option says.
Answer:

(10 x 10 18 times)(10 x 10 23 times) 
just as a note: when you multiply numbers with exponents and they both have the same base, all you have to do is add the exponents.
Ex: 
Answer:
9 inches
Step-by-step explanation:
The formula for the volume of a rectangular pyramid is 
- Here we have volume (V), base (L), and width (W)
- V = 360 in³, L = 12 in, W = 10 in
We need to manipulate the volume equation to solve for the height (H)
- First we need to multiply both sides by 3 to get rid of the fraction: 3V = L×W×H
- Then we need to divide both sides by (L×W) to get:
Now we can plug in the given values:
- The height is 9 inches