Vulcanization of rubber was discovered by: MCQ with Answer and Explanation

Explanation:
Alpha rays consist of ⁴₂He²⁺ particles (2 protons + 2 neutrons). They have low penetration but high ionization power.

Explanation:
Rutherford bombarded a thin gold foil with alpha particles. Most passed through, but some were deflected, leading to the nuclear model.

Explanation:
Wood has lower calorific value (~17 kJ/g) compared to coal (~25-35 kJ/g), methane (~55.5 kJ/g), and hydrogen (~142 kJ/g). It contains moisture and oxygen, reducing energy density.