Is I/V graph and V/I graph same? If no, then how come is sometimes V marked as x axis and I marked as y axis?
No.
In a V/I graph the V is along the Y axis and I along the X axis, where the resistance is the slope. In an I/V graph the I is along the Y axis and V along the X axis, where the resistance is 1 by slope.
In a V/I graph the V is along the Y axis and I along the X axis, where the resistance is the slope. In an I/V graph the I is along the Y axis and V along the X axis, where the resistance is 1 by slope.