For one mole of an ideal gas the slope of V vs. T curve at constant pressure of 2 atm is X lit mol–1 K–1. The value of the ideal universal gas constant ‘R’ in terms of X is
X lit atm mol–1K–1
X/2 lit atm mol–1K–1
2X lit atm mol–1K–1
2X atm lit–1mol–1K–1