Answer
6.00 atm
Work Step by Step
$V_{1}$ = 5.00 L
$p_{1}$ = 1.20 atm
$V_{2}$ = 1.00 L
According to Boyle's law, $p_{1}V_{1} = p_{2}V_{2}$
This implies that $p_{2}$ = $\frac{p_{1}V_{1}}{V_{2}}$ = $\frac{1.20atm\times5.00 L}{1.00 L}$ = 6.00 atm