Explanation

• Brass is an alloy mainly made of copper and zinc.
• In air, there are various gases including oxygen, carbon dioxide, moisture, and traces of hydrogen sulphide (H₂S).
• The gas responsible for discoloration of brass is hydrogen sulphide.
• Hydrogen sulphide reacts with copper present in brass to form copper sulphide.
• This copper sulphide forms a dark layer, causing brass to lose its shine and colour (tarnishing).

Last updated question by NS on 2 MAY 2026

Explanation

• Tetraethyl lead is primarily used as an antiknock agent
• Octane booster in gasoline and aviation fuel.
•  It prevents "knocking" (premature ignition of petrol vapors) in motors.
• Highly toxic and easily absorbed through the skin, lungs, and gastrointestinal tract

Last updated question by NS on 2 MAY 2026

Explanation

• Atoms of the same element with same protons but different neutrons are called isotopes.
• They have the same atomic number but different mass numbers.
• Isotopes show different physical properties but similar chemical behavior.
• Example: Hydrogen has Protium, Deuterium, and Tritium.

Last verified on 02-05-2026

Explanation

• Neon (Ne) has an atomic number 10
• Its electronic configuration is 2, 8
• The outermost shell (valence shell) contains 8 electrons
• This makes neon a stable noble gas

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Last updated by NS on 01 MAY 2026

Explanation

• Hydrogen (H2) and Argon is not a greenhouse gas.
• Greenhouse gases are gases that trap heat in Earth’s atmosphere and cause the Greenhouse Effect.

The main greenhouse gases are:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Water vapor (H2O)
• Ozone (O3)
• Chlorofluorocarbons (CFCs)
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)

Last verified on 01-05-2026