The reason for a piece of iron not floating on the surface of water is

The reason for a piece of iron not floating on the surface of water is that the weight of water displaced by iron is less than the weight of iron (option A). According to Archimedes’ principle, for an object to float, the buoyant force (weight of water displaced) must equal or exceed the weight of the object. Since iron is denser than water, it displaces less water than its own weight, causing it to sink. This principle explains why objects with a density greater than that of water, like iron, sink when placed in water. Therefore, the weight of water displaced by the iron determines whether it will float or sink, and in this case, it is less than the weight of the iron, leading to its submersion.