Vulcanization of rubber involves heating with: MCQ with Answer and Explanation

Explanation:
J.J. Thomson discovered the electron through cathode ray tube experiments in 1897 and measured the e/m ratio by applying electric and magnetic fields. Rutherford discovered the nucleus via the gold foil experiment. Chadwick discovered the neutron (1932). Bohr proposed the planetary model of the atom with quantized orbits. Thomson's model (plum pudding) was later superseded. Exam memory: Thomson = electron (e/m); Rutherford = nucleus; Chadwick = neutron; Bohr = energy levels.

Explanation:
Element 117 (tennessine, Ts) is a halogen in Group 17, Period 7. The modern periodic table has 7 periods and 18 groups. Halogens are in Group 17. Period 7 starts with Fr (87) and ends with Og (118). Ts is two places before Og. Exam trick: For atomic numbers after 86 (Rn), use period 7. Group 17 elements are F, Cl, Br, I, At, Ts.

Explanation:
High-concentration H₂O₂ (e.g., 80-90%) decomposes rapidly in the presence of a catalyst to produce superheated steam and oxygen: 2H₂O₂ → 2H₂O + O₂ + heat. This generates high-pressure gas used for propulsion (monopropellant) or as oxidizer in bipropellant systems. It is not a fuel; it provides oxygen for combustion. It must be handled carefully due to instability.