The answer to this is a. 20%
The answer should be D all of the above
Answer:

Explanation:
When heat is supplied to a substance, the temperature of the substance increases according to:

where
Q is the amount of heat supplied
m is the mass of the substance
C is the specific heat capacity of the substance
is the initial temperature
is the final temperature
For the sample of magnesium in this problem, we have:
m = 63 g is the mass
Q = 6689 J is the hear supplied
C = 1.023 J/gC is the specific heat capacity
is the final temperature
Solving the formula for
, we find the final temperature:

Answer:
Physical change
Explanation:
Chemical change is defined as the process in which new substance with different properties is formed from old substance and the process is irreversible while physical change is a reversible process and changes only physical properties of a substance.
<em>The given experiment is an example of physical change because it is just the physical act of dissolving. The metal disk is dissolving in sodium acetate and the process is exothermic and the process is reversible as well.</em>
Hence, the correct answer is "physical change".