The diagram shows JJ Thomson’s experiment with a cathode ray tube. positively charged metal plate. negatively charge metal plate
Which of the following conclusions about the particles in the cathode ray is most consistent with JJ Thomson’s experiment and observations?

The particles are positively charged.
No assumptions can be made from the experiment.
The particles are negatively charged.
The particles are neutral.

The particles are negatively charged.

Explanation:

Electron was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

He constructed the glass tube and create vacuum in it. He applied electric current between electrodes. He noticed that a ray of particles coming from cathode to wards positively charged anode. This ray was cathode ray.

Properties of cathode ray:

The ray is travel in straight line.

The cathode ray is independent of composition of cathode.

When electric field is applied cathode ray is deflected towards the positively charged plate.

Hence it was consist of negatively charged particles.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.