The chemical formula of Teflon is: MCQ with Answer and Explanation

Explanation:
Reactivity series orders metals according to their ease of oxidation—i.e., losing electrons to form cations. At the top (K, Na) are strong reducing agents, reacting vigorously with water and acids; at the bottom (Au, Pt) are noble metals, resistant to corrosion. The series helps predict displacement reactions and extraction methods. Mnemonic: 'Please Stop Calling Me A Cute Zebra...' etc.

Explanation:
Portland cement is primarily composed of tricalcium silicate (3CaO·SiO₂), dicalcium silicate (2CaO·SiO₂), tricalcium aluminate (3CaO·Al₂O₃), and tetracalcium aluminoferrite. These compounds are formed by heating limestone and clay at high temperatures and then grinding with gypsum.

Explanation:
CFCs were widely used as refrigerants (Freon), propellants in aerosol sprays, foam blowing agents, and solvents. They are chemically stable in the troposphere, drift to the stratosphere where UV breaks them, releasing Cl atoms that destroy ozone. Automobiles emit CO₂, NOx. Volcanoes emit SO₂. Fertilizers lead to N₂O.