What are the three stages in the pcr test? ( forensic science )

Separating the Target DNA—Denaturation. ...
Binding Primers to the DNA Sequence—Annealing. ...
Making a Copy—Extension.

First we can find the number of moles of gas for the given volume at STP and then calculate the new volume 
Molar volume states that there 1 mol of any gas occupies a volume of 22.4 L at STP.
Therefore if 22.4 L contains - 1 mol of gas
then 25.0 L contains - 25.0 L / 22.4 L/mol = 1.12 mol 
when the pressure and temperature conditions are changed the number of moles of gas remains the same 
using the ideal gas law equation we can find the volume of the gas
PV = nRT
where P - pressure - 605 torr x 133.3 Pa/torr = 80 647 Pa
V - volume 
n - number of moles - 1.12 mol 
R - universal gas constant - 8.314 Jmol⁻¹K⁻¹
T - temperature in kelvin - 55°C + 273 = 328 K
substituting these values in the equation 
80 647 Pa x V = 1.12 mol x 8.314 Jmol⁻¹K⁻¹ x 328 K
V = 37.9 L 
new volume at the given conditions is 37.9 L