Which of the following is a secondary air pollutant?
A. CO
B. SO₂
C. Lead
D. Ozone
Answer: Option D
Solution (By JKSSB Mock Tests)
Tropospheric ozone is not emitted directly; it forms by photochemical reactions of NOx and VOCs in sunlight. So it's a secondary pollutant. CO, SO₂, and lead are primary pollutants emitted directly from sources. Secondary pollutants include ozone, PAN (peroxyacetyl nitrate), and sulfuric acid mist. Ozone at ground level is harmful.
Explanation:
Dalton considered atoms the ultimate, indivisible particles. The discovery of electrons (J.J. Thomson), protons (Rutherford), and neutrons (Chadwick) proved atoms are divisible and have internal structure. Isotopes showed atoms of same element can differ. However, Dalton's theory still formed the foundation of modern chemistry.
Explanation:
Teflon is polytetrafluoroethylene (PTFE), a fluorocarbon polymer with extremely low coefficient of friction and high thermal stability, making it ideal for non-stick cookware. PVC (polyvinyl chloride) is used in pipes and cables. Polystyrene is used in packaging and insulation. Nylon is a polyamide used in textiles. Teflon is chemically inert and resistant to acids and bases.
Explanation:
Soap molecules have a hydrophilic ionic head (COO⁻Na⁺) and a long hydrophobic hydrocarbon tail. In water, the tails aggregate away from water, forming a spherical micelle with heads outward. The hydrophobic core dissolves oily dirt, which is then washed away. This structure is stabilized by ion-dipole interactions. Detergents work similarly but with different head groups.
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