Is the person below doing work on the briefcase yes or no and explain

Which is not true about oxygen-17 and oxygen-18?

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat

An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector inside a tv tube. the electron strikes the screen after traveling 26 cm horizontally and 19 cm vertically upward with no horizontal acceleration. what is the constant vertical acceleration provided by the deflector? (the effects of gravity can be ignored.)