Final answer:
Water's high surface tension and viscosity are due to strong hydrogen bonds between its molecules, which create a 'tough skin' on the surface and increase resistance to flow.
Step-by-step explanation:
Explaining the High Surface Tension and Viscosity of Water
Water exhibits relatively high surface tension and viscosity primarily due to the presence of hydrogen bonds between its molecules. These intermolecular hydrogen bonds are strong, causing water molecules to stick together and resist being pulled apart. As a result, the surface of water can be thought of as having a 'tough skin' that can support small objects due to the cohesive forces between the molecules.
Viscosity, the resistance of a liquid to flow, is also higher in water compared to many other liquids because the hydrogen bonds increase the amount of energy required to move molecules past one another. Substances with low intermolecular forces, such as low-boiling-point organic molecules, tend to have lower viscosity and surface tension. Observations such as a needle floating on water or insects walking on the surface are due to water's high surface tension.
Surfactants, like soap, reduce the surface tension of water by disrupting the hydrogen bonds. The essential application of this concept is seen in the beading of water droplets on surfaces, which is a direct consequence of high surface tension. The 'beading up' effect is because of the energy required to increase the surface area of these liquids, with water's surface tension measured at around 7.29 x 10-2 J/m² at 20°C.