One mole of an ideal gas undergoes an isothermal compression at 0 oC, and 7.5 x 103

Question:

One mole of an ideal gas undergoes an isothermal compression at 0 oC, and 7.5 x 103 J of work is done in compressing the gas.
(a) Will the entropy of the gas (1) increase, (2) remain the same, or (3) decrease? Why?
(b) What is the change in entropy of the gas?