Gases begin to conduct electricity at low pressure, because

Options

A. At low pressure, gases turn to plasma
B. Colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms
C. Atoms break up into electrons and protons
D. The electrons in atoms can move freely at low pressure

Answer

B

Explanation

At low pressure, the density of the gas decreases. The mean free path of the gas molecules becomes large. Under the effect of external high voltage, the ions acquire sufficient energy before they collide with molecules, causing further ionisation.