Detailed Analysis of Spray and Dust Drift:

• Statement (I) is Correct: Pesticide dusts consist of microscopic dry powder particles ($\lt 20\text{--}30\ \mu\text{m}$) that have extremely low mass and terminal settling velocity, making them highly prone to long-distance airborne drift even under mild air currents. Consequently, chemical recovery in target fields from dusting rarely exceeds 10–20% compared to 70–80% for liquid sprays.
• Statement (II) is Incorrect: Droplets with small Volume Mean Diameter (VMD $\lt 100\text{--}150\ \mu\text{m}$) evaporate rapidly and remain suspended in air, causing severe drift. To minimize spray drift, operators must INCREASE the VMD (producing larger, coarser droplets $\gt 250\text{--}300\ \mu\text{m}$) and use air-induction nozzles.

Hollow cone nozzles produce fine droplets with excellent foliage penetration and wrap-around coverage under leaves, making them ideal for foliar application of insecticides and fungicides. Flat fan and flooding nozzles produce coarser droplets and are preferred for herbicide application. Option analysis: (A) Hollow cone provides the fine droplets and dense coverage needed for insect and disease control. (B) Solid cone is used for soil drenching and spot treatment. (C) Flat fan is standard for herbicide boom spraying. (D) Flooding nozzle is used for high-volume herbicide/fertilizer spraying.

By Torricelli's orifice equation, discharge through an orifice is $Q = C_d A \sqrt{2gH} = C_d A \sqrt{\frac{2P}{\rho}}$. Therefore, nozzle discharge $Q \propto \sqrt{P}$ (directly proportional to the square root of operating pressure). To double the flow rate, pressure must be quadrupled. Option analysis: (A) Flow rate is not linearly proportional to pressure. (B) Flow rate increases with pressure, not inverse. (C) Directly proportional to square root of pressure is the exact orifice hydraulic relationship. (D) Incorrect power.