Which of the following is not a use of silicon?

Silicon is a non-metallic element belonging to group 14 of the periodic table. It is the second most abundant element in the Earth’s crust, found mainly as silica (SiO₂) and silicates. Due to its versatile chemical properties, silicon and its compounds are widely used in many industrial and household applications.

One of the major uses of silicon is in the form of silicones, which are organosilicon polymers. Silicones are stable, flexible, and resistant to heat and chemicals. They are used as lubricants, sealants, adhesives, and water-repellent coatings. Their non-reactive and smooth nature makes them ideal for preventing friction and protecting surfaces.

Silicones are also used in antifreeze formulations. In such applications, they help lower the freezing point of liquids and provide long-term stability. Another important use of silicon is in electronics. Pure silicon is a semiconductor material, which makes it essential for making integrated circuits, solar cells, and computer chips.

However, hydraulic brakes do not use silicon or its compounds as a primary component. Hydraulic brakes operate on the principle of fluid pressure transmission, typically using glycol-based or mineral oil fluids. These fluids are designed for optimal compressibility and viscosity, not for properties associated with silicon.

In contrast, silicon-based materials are used where thermal stability, electrical insulation, or surface protection is required, not for mechanical hydraulic systems. Therefore, among the given options, hydraulic brakes are not a use of silicon.