Explanation

• Arsenic is a toxic substance that can contaminate groundwater and cause serious health problems after prolonged exposure.
• Water sources confirmed to have excessive arsenic should be clearly marked, and people should be advised not to use them for drinking or cooking.

Last verified on 21-10-2026

Explanation

• Nitrogen (N₂) makes up about 78% of Earth's atmosphere. 
• It is generally not considered an air pollutant in its normal form.

Additional information:

• Hydrocarbons can contribute to air pollution by reacting with nitrogen oxides to form ground-level ozone.
• Chromium, especially certain compounds such as hexavalent chromium, can pollute the air and pose serious health risks.
• Carbon dioxide (CO₂) is a greenhouse gas that contributes to global warming and is also classified as an air pollutant in some environmental frameworks.

Last verified on 21-10-2026

Explanation

• Sulphur dioxide (SO₂) is used as a dechlorinating agent to remove residual chlorine from water.
• It reacts with chlorine and reduces it to chloride ions, thereby neutralizing its disinfecting effect.
• Dechlorination is commonly required when excess chlorine must be removed from treated water or wastewater.

Last verified on 17-10-2026

Explanation

• Amino acids are the building blocks of proteins.
• Proteins are formed when amino acids join together by peptide bonds.
• Proteins are essential for growth, repair, and body functions.
• There are 20 standard amino acids used to make proteins.

Verified & Updated

Explanation

• Sublimation is the process in which a solid directly changes into a gas without passing through a liquid phase.
• This endothermic phase transition
• Occurs when a substance absorbs enough energy to overcome intermolecular forces.
• Deposition: Gas to Solid (the reverse process).
• Examples: Dry ice, iodine, frost/snow.