The activation energy is the minimum required energy in order to start a reaction. It is the barrier to break to enable reactants to form products. It is not important only for some reactions but to all reactions. This energy should be supplied or reached first before we observe a reaction to happen.
Gay-Lussac's law gives the relationship between pressure and temperature of gas. For a fixed amount of gas, pressure is directly proportional to temperature at constant volume.
P/T = k
where P - pressure , T - temperature and k - constant

parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation
substituting the values in the equation

T = 4342 K
initial temperature was 4342 K
In order to solve this, we have to know the density of acetone because it is the ratio of mass to volume. At a certain temperature and pressure, the density of a specific substance does not change. It is an intrinsic property of a substance with temperature and pressure dependence. Assuming this is in normal conditions, the density is equal to 0.784 g/mL. So, the volume would be equal to
Volume = Mass/Density
Volume = 7.66 g/0.784 g/mL = 9.77 mL
I believe the correct answer from the choices listed above is option 2. From the balanced equation, the energy is absorbed as the bonds are broken. Energy is needed to be supplied for the bonds to be broken.
Hope this answers the question. Have a nice day.