Option 1 states that the surface tension of water vanishes immediately when oil floats on water. However, this is incorrect. Surface tension is the force that exists at the surface of a liquid, causing it to behave as if it has a thin elastic skin. When oil floats on water, the surface tension of water does not disappear completely.

Option 2 states that the surface tension of water decreases considerably when oil floats on water. This option is correct. Oil has a different molecular structure compared to water, which disrupts the cohesive forces between water molecules at the surface. This disruption results in a decrease in the surface tension of water. As a result, the water`s ability to hold together and form droplets or maintain its shape is reduced.

Option 3 states that the surface tension of water increases considerably when oil floats on water. This is incorrect. The presence of oil floating on the water does not cause the surface tension of water to increase considerably. Rather, it decreases.

Option 4 states that the surface tension of water remains unaffected when oil floats on water. This is incorrect. As mentioned earlier, the surface tension of water decreases considerably when oil floats on it.