Answer
(a) 50. mL
(b) 10. mL
(c) 6.1 mL
(d) 190 mL
Work Step by Step
1. Conversion factors:
$1 \space atm = 760 \space mmHg (exact)$
$1 \space atm = 760 \space Torr (exact)$
2. According to the Boyle's Law:
$$P_1V_1 = P_2V_2 \longrightarrow \frac{P_1V_1}{P_2} = V_2$$
(a) $$V_2 = \frac{(0.80 \space atm)(25 \space mL)}{0.40 \space atm} = 50. \space mL$$
(b)
$$V_2 = \frac{(0.80 \space atm)(25 \space mL)}{2.00 \space atm} = 10. \space mL$$
(c)
$P_2 = 2500 \space mmHg \times \frac{1 \space atm}{760 \space mmHg} = 3.3 \space atm$
$$V_2 = \frac{(0.80 \space atm)(25 \space mL)}{3.3 \space atm} = 6.1 \space mL$$
(d)
$P_2 = 80.0 \space Torr \times \frac{1 \space atm}{760 \space Torr} = 0.105 \space atm$
$$V_2 = \frac{(0.80 \space atm)(25 \space mL)}{0.105 \space atm} = 190 \space mL$$
