Answer: The final pressure is 75 mm Hg.
Explanation:
According to Boyle's law, at constant temperature the pressure of a gas in inversely proportional to volume.
Since, it is given that the temperature is constant. Hence, formula used is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that the final pressure is 75 mm Hg.
Answer: 0.5 mole Mg
Explanation: solution:
12 g Mg x 1 mole Mg / 24 g Mg
= 0.5 mole Mg
B) energy is absorbed by the reaction
is right answer.