Which of the following polymers is a thermosetting plastic? MCQ with Answer and Explanation

Explanation:
CO₂ levels have risen due to burning fossil fuels, enhancing greenhouse effect. Methane, N₂O also contribute. Nitrogen and oxygen are not greenhouse gases.

Explanation:
Catalytic converters use precious metals like platinum, palladium, and rhodium as catalysts to convert toxic exhaust gases (CO, NOx, unburnt hydrocarbons) into less harmful substances (CO₂, N₂, H₂O) before they are released into the atmosphere. These metals are chosen for their high catalytic activity and durability.

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.