Answer
Please see the work below.
Work Step by Step
We know that the area is
$A=\pi r^2$
$A=(3.1416)(\frac{0.0015}{2})^2=7.67\times 10^{-6}m^2$
The pressure is
$P=120atm=(120)(1.01\times 10^5)Pa=1.212\times 10^7Pa$
Now we can find the force as
$F=PA$
$F=(1.212\times 10^7)(1.767\times 10^{-6})$
$F=21N$
