Given below are the critical temperatures of some of the gases :
Gas | Critical temperature (K) |
---|---|
He | 5.2 |
CH4 | 190.0 |
CO2 | 304.2 |
NH3 | 405.5 |
The gas showing least adsorption on a definite amount of charcoal is
Extent of adsorption ∝ TC (critical temperature)
∵ Lower the TC, Lower will be the adsorption
Hence, Helium shows least adsorption on a definite amount of charcoal.
So, the correct option is (A): He.
A sealed flask with a capacity of $2\, dm ^3$ contains $11 \, g$ of propane gas The flask is so weak that it will burst if the pressure becomes $2\, MPa$ The minimum temperature at which the flask will burst is ______${ }^{\circ} C$ [Nearest integer]
(Given: $R =8.3 \,J \,K ^{-1} mol ^{-1}$ Atomic masses of $C$ and $H$ are $12\, u$ and $1 \,u$ respectively) (Assume that propane behaves as an ideal gas)
The temperature dependence of resistance is a fundamental property of all materials that conduct electricity. Generally, the resistance of a conductor increases with an increase in temperature. This phenomenon is known as a positive temperature coefficient of resistance.
The reason for this temperature dependence of resistance is related to the interaction of electrons with the crystal lattice of the material. At lower temperatures, the lattice vibrations are minimal, and the electrons are free to move through the material with minimal scattering. This results in a low resistance to the flow of current. However, as the temperature increases, the lattice vibrations increase, causing the electrons to scatter more frequently, which increases resistance.
This phenomenon is governed by the relationship between resistance and temperature known as the temperature coefficient of resistance. The temperature coefficient of resistance is defined as the rate at which resistance changes with respect to temperature. The temperature coefficient of resistance is positive for most metals and semiconductors, meaning that resistance increases with increasing temperature.
However, there are a few materials, such as carbon and certain semiconductors, which exhibit a negative temperature coefficient of resistance. In these materials, the resistance decreases as the temperature increases.
The temperature dependence of resistance has important practical implications in the design and operation of electrical circuits and devices. For example, it is essential to consider the effect of temperature on the resistance of electronic components to ensure reliable and efficient operation of devices over a range of temperatures.