Explanation

• Nitrogen (N2) makes up about 78% of the Earth's atmosphere.
• Making it the most abundant gas in the atmosphere.
• It is followed by oxygen (~21%), with other gases in much smaller amounts.

Last verified on 15-03-2026

Explanation

• Symbol: Hg
• Atomic number: 80
• Melting point: -38.83 °C
• Atomic mass: 200.59 u

Last verified on 13-03-2026

Explanation

• Hydrogen and helium are the two lightest gases.
• Helium is the second most abundant element in the universe, after hydrogen.
• Helium has monatomic molecules.
• It is the lightest of all gases except hydrogen.
• Hydrogen is the lightest gas known.
• It provides the maximum lift for balloons due to its very low density.

Last updated question 17-02-2026

Explanation

• Examples: Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn)
• Reason for Inactivity: Complete valence electron shell → chemically stable

Additional information:

• Rarely form compounds, mostly inert
• Used in lighting (Neon lights), welding (Argon), and as inert environments in laboratories

Last verified on 08-02-2026

Explanation

• Refrigerants are gases used in refrigerators to absorb heat and provide cooling.
• Freon (CFCs) and ammonia are commonly used in domestic and commercial refrigeration.
• They evaporate at low temperatures, absorbing heat from the fridge interior.
  

Last verified on 03-02-2026