The tendency of an atom to gain electrons is known as: MCQ with Answer and Explanation

Explanation:
In 1911, Ernest Rutherford conducted the gold foil experiment, firing alpha particles at a thin gold sheet. While most passed through, a few were deflected at large angles, and some bounced back. This led him to conclude that the atom's positive charge and most of its mass are concentrated in a tiny, dense central core called the nucleus.

Explanation:
Mendeleev arranged elements in order of increasing atomic mass and grouped elements with similar chemical properties. He left gaps for undiscovered elements like eka-aluminium (gallium) and eka-silicon (germanium), predicting their properties. The modern table uses atomic number as the basis. Mendeleev's table had anomalies like placing Ar (40) before K (39) due to mass order, later resolved by atomic number concept.

Explanation:
H₂S is oxidized (S²⁻ → S, loss of electrons), so it acts as the reducing agent. FeCl₃ is reduced (Fe³⁺ → Fe²⁺) and acts as oxidizing agent. The substance oxidized is the reducing agent.