Among the gases a , b , c , d , e and f , the gases that show only positive deviation from ideal behavior at all pressures in the graph are

Step-by-step solution

When Z   <   1 , it is a negative deviation. It shows that the gas is more compressible than expected from ideal behaviour. When Z   >   1 , it is a positive deviation. It shows that the gas is less compressible than expected from ideal behaviour. Only b and c gases showing exclusive positive deviation.