Who discovered proton? 

E. Rutherford

The correct answer is option 1. E. Rutherford.

Ernest Rutherford is credited with the discovery of the proton. Here's an explanation of his contribution:

1. Experimental Observations:  In the early 20th century, Rutherford conducted experiments involving the bombardment of various materials with alpha particles (positively charged helium nuclei). One of the significant experiments was the famous gold foil experiment, conducted in 1909.

2. Gold Foil Experiment:  In the gold foil experiment, Rutherford and his colleagues directed a beam of alpha particles at a thin foil of gold. They expected the alpha particles to pass through the gold foil with minimal deflection, based on the prevailing model of the atom at the time, known as the "plum pudding" model proposed by J.J. Thomson.

3. Unexpected Results: Contrary to expectations, some of the alpha particles were deflected at wide angles, and a few even bounced directly back. This unexpected scattering pattern led Rutherford to propose a new model of the atom.

4. Discovery of the Nucleus:  Rutherford interpreted the results of the gold foil experiment as evidence that the positive charge of the atom and most of its mass were concentrated in a small, dense region at the center of the atom, which he termed the "nucleus." This nucleus was postulated to contain positively charged particles that repelled the positively charged alpha particles, causing them to deflect.

5. Identification of the Proton:  Based on the concept of the nucleus, Rutherford proposed that the positively charged particles within the nucleus were fundamental constituents of the atom. He named these positively charged particles "protons."

6. Confirmation: Subsequent experiments and advancements in particle physics confirmed the existence of the proton and its role as a fundamental subatomic particle with a positive electric charge. The proton was identified as one of the building blocks of atomic nuclei, along with neutrons.

In summary, Ernest Rutherford's discovery of the proton, based on his interpretation of the results of the gold foil experiment, was a crucial development in the field of atomic physics. It provided foundational insights into the structure of the atom and laid the groundwork for further advancements in our understanding of subatomic particles and atomic nuclei.