What partial pressure of hydrogen gas is required in order for 0.00426 g of the gas to dissolve in 20.7 mL of pure water? The Henry's law constant for hydrogen gas is 7.8 x 10 ^-4 M atm^-1.
A. 1.6 x 10^-3 atm
B. 1.6 x 10^-7 atm
C. 7.6 x 10^-3 atm
D. 1.6 x 10^-6 atm
E. 1.3 x 10^2 atm