What is the primary reason pavements are slick just after rain on a hot day?

• A. Water on asphalt freezes
• B. Oil on the asphalt rises to the surface due to heat
• C. Soap or detergent residue on road
• D. Rainwater alone makes it slippery

Answer: (B)

Hot pavement drives oils in the asphalt to the surface. When rain arrives on a hot day, a very thin film of that oil sits on top of the water, creating a slick layer that greatly reduces traction. Water alone isn’t enough to explain the intense slipperiness here; the oil film is the main factor. The other factors, like residue from soap or detergents or water freezing, don’t fit the hot-weather scenario. So the slickness comes from the oily film rising to the surface and spreading with the rain.