For the solution of the gases w, x, y and z in water at 298 K, the Henry's law constants (K$$_H$$) are 0.5, 2, 35 and 40 kbar, respectively. The correct plot for the given data is:

According to Henry's Law: $$p = K_H \cdot x_{\text{gas}}$$

Since $$x_{\text{gas}} + x_{\text{water}} = 1$$, substituting gives:

$$p = K_H(1 - x_{\text{water}}) = K_H - K_H \cdot x_{\text{water}}$$

This matches a straight line equation ($$y = mx + c$$) where:

• Y-intercept ($$c$$): $$K_H$$ (Higher $$K_H$$ means a higher intercept on the partial pressure axis)
• Slope ($$m$$): $$-K_H$$ (Higher $$K_H$$ means a steeper negative slope downward)

Ordering:

Given $$K_H$$ values: $$\text{z (40)} > \text{y (35)} > \text{x (2)} > \text{w (0.5)}$$

Therefore, gas $$z$$ has the highest starting intercept and slopes downward the steepest, while gas $$w$$ has the lowest intercept.

Conclusion:

Option A correctly displays downward-sloping lines ordered from top to bottom as z, y, x, w.

Answer: Option A