Question

X is a separation technique based on the difference in size and color of desirable and undesirable constituents? What is X?

Answer 1

it's Winnowing

In winnowing, light weight impurities are separated from relatively heavier substances. For example, husk is separated from wheat. It is done by releasing the mixture into the air so that the wind blows away the lighter impurities, while the heavier grains fall back down for recovery.