An electron collides with a free molecules initially in its ground state. The collision leaves the molecules in an excited state that is metastable and does not decay to the ground state by radiation. Let K be the sum of the initial kinetic energies of the electron and the molecule, and `vecP` the sum of their initial momenta. Let K' and `vecP` represent the same physical quantities after the collision. Then

Options

A. `K = K' , vecP = vecP`
B. `K lt K' , vecP = vecP`
C. `K = K' , vecP ne vecP`
D. `K' lt K' , vecP ne vecP`

Answer

B

Explanation

Collision of electron lead to excitation of molecules so collision is inelastic
`:. K.lt K` and loss of kinetic energy is used for excitation of molecules. Momentum remains conserved during collision. `vecP = vecP` ......