Atoms are Composed of-
Answer: 4. Electrons and nuclei;
An atom is the smallest constituent unit of ordinary matter, it is consists of a nuclei (it is consist of protons and neutrons) and electrons, electrons bound the nucleus. the atomic nucleus was discovered in 1911 by Ernest Rutherford based on the 1909 Geiger- Mars den gold foil experiment. The protons have a positive electric charge , electrons have negative electric charge, and the neutrons have no electric charge.