Answer:
c. 0.750 atm .
Step-by-step explanation:
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In this case, since the two vessels have different volume, we can see that the gas is initially at 3.00 atm into the 1.00-L vessel, but next, it is allowed to move towards the 3.00-L vessel, meaning that the final volume wherein the gas is located, is 4.00 L; therefore, we use the Boyle's law to compute the final pressure:

Therefore the answer is c. 0.750 atm .
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