1) For alloys value of temperature coefficient is very high (false)

The value of the temperature coefficient of resistance is a measure of how much the resistance of a material changes with temperature. It is denoted by the symbol α and is expressed in units of ohms per degree Celsius (Ω/°C).

Alloys are metallic materials that are composed of two or more elements, with at least one of them being a metal. Examples of alloys include brass (copper and zinc), stainless steel (iron, chromium, and nickel), and bronze (copper and tin). The temperature coefficient of resistance for alloys can vary depending on their composition.

It is not accurate to say that the value of the temperature coefficient is very high for alloys in general. The temperature coefficient of resistance for alloys can be positive, negative, or close to zero, depending on the specific alloy and its composition.

2) For metallic conductors the value of temperature coefficient of resistance is negative (true)

For metallic conductors, such as copper, silver, and aluminum, the value of the temperature coefficient of resistance is indeed negative. This means that as the temperature increases, the resistance of the conductor decreases.

This negative temperature coefficient of resistance can be explained by the behavior of the electrons in metallic conductors. As the temperature increases, the atoms in the conductor vibrate more vigorously, which leads to more frequent collisions between the electrons and the atoms. These collisions impede the flow of electrons, resulting in an increase in resistance.

However, the increased thermal energy also causes the electrons to move more rapidly, counteracting the increase in resistance to some extent. The net effect is a decrease in resistance with increasing temperature, giving metallic conductors their negative temperature coefficient of resistance.

This property of metallic conductors can be advantageous in applications where the resistance needs to be kept relatively constant over a wide range of temperatures. For example, in electrical wiring, the negative temperature coefficient of resistance helps to compensate for the increase in resistance due to heating, ensuring that the electrical conductivity remains relatively constant.

In summary, the value of the temperature coefficient of resistance for metallic conductors is negative, indicating that the resistance decreases as the temperature increases.