The study of discharge of electricity through gases led to the discovery of

Options

A. Structure of the atom
B. Nucleus
C. Spectral lines
D. Electron

Answer

**Step-by-Step Solution:**

1. **Understanding the Experiment**: The question refers to the experiments conducted on the discharge of electricity through gases. This involves using a discharge tube, which is a sealed glass tube containing a gas at low pressure.

2. **Identifying the Key Experiment**: The first significant experiment in this area was conducted by William Crookes. He used a cathode ray tube (CRT) to explore the behavior of electric currents in gases.

3. **Setting Up the Discharge Tube**: In Crookes' experiment, he placed two electrodes (a cathode and an anode) inside the tube and applied a high voltage across them. This setup allowed electricity to flow through the gas, causing it to emit light.

4. **Observing the Results**: When the high voltage was applied, a stream of particles was observed moving from the cathode to the anode. This stream was later identified as a beam of negatively charged particles.

5. **Further Research by J.J. Thomson**: Building on Crookes' work, J.J. Thomson conducted further experiments and concluded that these particles were much smaller than atoms and carried a negative charge. He named them "electrons."

6. **Conclusion**: Therefore, the study of the discharge of electricity through gases ultimately led to the discovery of electrons.

**Final Answer**: The study of discharge of electricity through gases led to the discovery of electrons.

---