Answer
2.40 atm
Work Step by Step
$V_{1}$ = 5.00 L
$p_{1}$ = 1.20 atm
$V_{2}$ = 2500. mL = 2.500 L
According to Boyle's law, $p_{1}V_{1} = p_{2}V_{2}$
⇒ $p_{2}$ = $\frac{p_{1}V_{1}}{V_{2}}$ = $\frac{1.20atm\times5.00 L}{2.500 L}$ = 2.40 atm