What does cathode rays have? 

Both mass and charge 

The correct answer is option 3. Both mass and charge.

Cathode rays are streams of electrons that are emitted from the cathode (negative electrode) in a vacuum tube, such as a cathode ray tube (CRT). These electrons are negatively charged particles with a small but finite mass. Here's a more detailed explanation:

1. Mass of Cathode Rays: Electrons, which constitute cathode rays, have a mass that is approximately \(9.109 × 10^{-31}\) kilograms. While this mass is incredibly small compared to everyday objects, it is still a significant characteristic of cathode rays. This mass allows cathode rays to interact with other objects and be influenced by forces such as gravity.

2. Charge of Cathode Rays: Electrons are negatively charged particles. This means that cathode rays possess a negative charge. This charge is fundamental to the behavior of cathode rays and plays a crucial role in their interaction with electric and magnetic fields.

3. Behavior in Electric and Magnetic Fields: Due to their negative charge, cathode rays are repelled by negatively charged objects and attracted to positively charged objects. They also experience deflection in the presence of electric and magnetic fields. This behavior can be observed in cathode ray tubes, where electric and magnetic fields are used to manipulate the path of cathode rays to produce images on a screen.

In summary, cathode rays possess both mass and charge. Their mass allows them to have inertia and be influenced by forces like gravity, while their charge dictates their behavior in electric and magnetic fields.