Correct expression to calculate reversible isothermal work of expansion is

• A

  $-{\mathrm{p}}_{\mathrm{ext}}\mathrm{\Delta V}$

• B

  $+{\mathrm{V}}_{\mathrm{ext}}∆\mathrm{P}$

• C

  $-2.303\mathrm{nRTlog}\frac{{\mathrm{v}}_{\mathrm{f}}}{{\mathrm{v}}_{\mathrm{i}}}$

• D

  $-2.303\mathrm{nRTlog}\frac{{\mathrm{p}}_{\mathrm{f}}}{{\mathrm{p}}_{\mathrm{i}}}$