n moles of a gas fille in a a container temperature T is in thermodynamic equilibrium initially. If the gas is compressed slowly and isothermally so half its initial volume volume the work done by the atmosphere on the piston is :
A. `(nRT)/(2)`
B. `-(nRT)/(2)`
C. `nRT("ln" 2 - 1/2)`
D. `-nRT "ln" 2`
