Velocity of electrons ejected from Cl atom
It would be the $3s$ shell because less energy is required to bump it off course. Due to electron repulsion and the shielding effect, the $e-$ in the $3s$ is more prone to get dislodged. And of course because of this, it will have a higher velocity when it gets bumped off. Another concept to note: $e-$ will have more energy at higher energy levels.

A reason why it wouldn't be the $1s$ shell is because due to the strong pull on the $1s$ electron. Since it is on the first energy level, it is strongly held by the nucleus. Even it were to get dislodged it would move very slow because of the strong pull by the nucleus.