The value of ΔGo for the precipitation reaction,
Ca2+(aq) + CO32-(aq) <=> CaCO3(s) is -48.1 kJ at 298 K.
Calculate the value of ΔG in kJ at 298 K if the concentrations of Ca2+(aq) and CO32-(aq) are 0.312 and 0.898, M respectively.

Explanation:

We know,

where Q is the reaction quotient and for this reaction, it is expressed as-

where species under third bracket represent concentrations in molarity.

T represents temperature in kelvin scale

Here T = 298 K

R = gas constant = 8.314 J/K

So,

or,

or,

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

i think that the answer is c