ANS:C - both (a) and (b).

The correct option is: neither (a) nor (b). Gases with the same reduced temperatures and reduced pressures do not necessarily deviate from ideal gas behavior to the same degree, nor do they necessarily have nearly the same compressibility factor.

1. Deviation from Ideal Gas Behavior: The deviation of a real gas from ideal gas behavior depends on various factors such as intermolecular forces, molecular size, and molecular shape. Even if gases have the same reduced temperatures and reduced pressures, they may exhibit different degrees of deviation from ideal behavior based on these factors.
2. Compressibility Factor: The compressibility factor (Z) of a gas is a measure of how much it deviates from ideal behavior under given conditions of temperature and pressure. Gases with similar reduced temperatures and reduced pressures may or may not have nearly the same compressibility factor. The compressibility factor depends on the specific gas and the conditions of temperature and pressure.

Therefore, gases with the same reduced temperatures and reduced pressures do not necessarily exhibit the same degree of deviation from ideal gas behavior, and they may not have nearly the same compressibility factor. Hence, the correct option is neither (a) nor (b).