Question

Properties of water which provide high tensile strength (i.e., ability to resist a pulling force) are: (a) Cohesion (b) Adhesion (c) Surface tension (d) All of these

Short answer

The properties of water which provide high tensile strength are all of the above (Cohesion, Adhesion, and Surface Tension).

Step-by-step solution

Understanding Cohesion

Cohesion is the property of like molecules (same substance) to stick to each other due to mutual attraction. In water, it is the intermolecular hydrogen bonding between the water molecules that results in a high cohesive force.

Understanding Adhesion

Adhesion is the property of unlike molecules (different substances) to stick to each other. In water, its polar nature has a strong attraction to other charged or polar surfaces. This also contributes to water's tensile strength.

Understanding Surface Tension

Surface tension is a measure of the strength of the water's surface. It is a direct result of the cohesive forces of water molecules attracting each other creating a 'film' on the surface. This property gives water its ability to resist external force.

Final Assessment

Based on these explanations, it can be concluded that all these properties (cohesion, adhesion, and surface tension) contribute to the high tensile strength of water.

Key concepts

Cohesion

Cohesion is an essential property of water, where molecules of the same kind tend to stick together. This phenomenon occurs because of the mutual attraction between molecules. In the case of water, this is primarily due to hydrogen bonds formed between the molecules. Each water molecule can form up to four hydrogen bonds with surrounding molecules, creating a strong network of connections.

These hydrogen bonds result in significant cohesive forces, allowing water to maintain its structure and not easily split apart. This cohesion not only explains how water droplets form but also provides water with high tensile strength, enabling it to resist pulling forces. These cohesive forces make water an excellent medium for transporting nutrients and minerals in plants from roots to leaves, a process vital for plant life.

In summary, cohesion helps water resist external forces by sticking together, which is why you often see water forming droplets or streaming consistently without breaking apart easily.

Adhesion

Adhesion is another critical property of water. It describes the tendency of water molecules to stick to different, often polar or charged, surfaces. Water's polar nature contributes significantly to its adhesive properties. A water molecule consists of a slightly positive hydrogen side and a slightly negative oxygen side, which attracts other polar molecules and surfaces.

This property is important in various natural processes like capillary action, where water can move through small spaces against gravity by adhering to walls of plant cells or even thin tubes. Without adhesion, water would not be able to climb up plant stems or adhere to surfaces like our skin, which is important for hydration and other biological processes.

Adhesion allows water to bond with other substances, allowing it to spread rather than be repelled. This is why water can coat surfaces and not just form blobs like mercury, which has very low adhesion.

Surface Tension

Surface tension is a fascinating property of water resulting from cohesion. It creates a film-like surface on the water caused by water molecules being pulled together at the surface. This thin film is due to the tight network of hydrogen bonds that forms among water molecules.

• Water molecules at the surface experience a stronger cohesion with the molecules beside and below them, rather than those above (since there's only air above), leading to a minimized surface.
• Surface tension allows lightweight insects like water striders to "walk" on water without breaking the surface.

Surface tension also affects everyday phenomena, like how water beads up on a smooth surface and bubbles form. This property is not only critical for some life forms but also holds applications in technology and science, from pharmaceuticals to respiratory functions in living organisms. In summary, surface tension helps water resist external forces more effectively than most liquids, contributing to its unique behaviors in nature and technology.