Answer is c photosynthesis
I think I it’s gonna be C.
You have to use the equation PV=nRT.
P=pressure (in this case 1.89x10^3 kPa which equals 18.35677 atm)
1V=volume (in this case 685L)
n=moles (in this case the unknown)
R=gas constant (0.08206 (L atm)/(mol K))
T=temperature (in this case 621 K)
with the given information you can rewrite the ideal gas law equation as n=PV/RT.
n=(18.35677atm x 685L)/(0.08206atmL/molK x 621K)
n=246.8 moles
Following reaction occurs in the given electrochemical system:

→ Fe +

Thus, under standard conditions
E(0) = E(0) Fe2+/Fe - E(0) Zn2+/Zn
where,

= standard reduction potential of Fe2+/Fe = -0.44 v

= standard reduction potential of Zn2+/Zn = -0.763 v
E(0) = 0.323 v
now, we know that, ΔG(0) =-nFE(0) ............... (1)
Also, Δ

On equating and rearranging equation 1 and 2, we get
K = exp(

)= exp (

) = 8.46 x
Answer:
moles = given mass/atomic mass
so H2O mass = 2 +16=18
so 12g of h2o= 12/16 = 3/4 moles