> A sample of 1.00 mol perfect gas molecules with $C_{p,\mathrm m} = 7R/2$ is put through the following cycle: (a) **constant-volume heating to twice its initial volume**, ...

(Problem 2.5, Atkins *Physical Chemistry* 8th ed.)

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The problem says that in a constant volume process the final volume is twice the initial volume. 

Is this even possible? How can volume become twice if it was constant all the time, it wouldn't have exploded to twice its size suddenly after the process ended right?