An ideal gas expands isothermally from ${10}^{-3}{m}^3 to {10}^{-2} m^3$ at 300 K against a constant pressure of ${10}^5 N{m}^{-2}$. The work done by  the gas is:

1. +270 kJ

2. -900 J

3. +900 kJ

4. -900 kJ

The work done when 1 mole of gas expands reversibly and isothermally from pressure of 5 atm to 1 atm at 300 K is

(Given log 5=0.6989 and R=8.314 J K^-1 mol^-1)
1.  zero J
2.  150 J
3.  +4014.6 J
4.  -4014.6 J