Beta rays are composed of: MCQ with Answer and Explanation

Explanation:
Radioactive decay is a spontaneous process where an unstable atomic nucleus loses energy by emitting radiation. Since it involves the emission of particles (protons, neutrons, electrons) from the nucleus, it fundamentally alters the nucleus, making it a nuclear, not chemical, process.

Explanation:
Portland cement is made by heating a mixture of limestone (CaCO₃) and clay (containing SiO₂, Al₂O₃, Fe₂O₃) in a rotary kiln at high temperature, forming clinker, which is then ground with a small amount of gypsum to control setting. Gypsum alone is added as a retarder, not raw material. The major compounds formed are tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.

Explanation:
Calorific value is determined using a bomb calorimeter, where a known mass of fuel is burnt in excess oxygen in a sealed bomb, and the heat released is absorbed by a known mass of water. Temperature rise is measured. Corrections for cooling, wire, and acid formation are applied. Units: kJ/kg or kJ/mol. The bomb calorimeter works at constant volume.