Answer
$1.8g$
Work Step by Step
We can find the required mas as follows:
$\Delta m=\frac{\pi D^2CM}{4RT}\Delta p$
We plug in the known values to obtain:
$\Delta m=\frac{\pi(0.022)^2(2)(28)}{4(8.31)(293)}(758000-552000)$
$\implies \Delta m=1.8g$