Explanation

NOTE: Hydrogen is the lightest gas, but Helium is generally preferred. However, since "Helium" is not listed among your choices, the correct answer from the provided options is Hydrogen

• Helium is the lightest safe gas commonly used for:
• Party balloons
• Advertisement balloons
• Weather balloons

Common MCQ Confusion

• Hydrogen is actually the lightest gas overall, but it is highly flammable and can catch fire.
• Helium is slightly heavier than hydrogen but is non-flammable and safe, so it is used in balloons.

Last verified on 18-03-2026

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

• 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

Explanation

Explanation

• The Sui Gas Field, located near Sui in Balochistan Province, Pakistan.
• It was discovered by Pakistan Petroleum Limited in 1952.
• Production of Sui gas began in 1955.
• It remains the largest natural gas field in Pakistan.

Explanation

• Carbon dioxide (CO₂) plays a crucial role in maintaining Earth’s atmospheric temperature.
• It traps heat through the greenhouse effect, keeping the planet warm enough for life.

Additional information:

• CO₂ levels in 2025 reached ~421 ppm (parts per million) globally.
• Plants absorb CO₂ for photosynthesis, partially regulating its atmospheric concentration.

Last verified on 17-01-2026

Explanation

Explanation

Argon is chemically inert and does not easily form compounds, a key property of noble gases.

It belongs to Group 18 of the periodic table, which contains all noble gases.

Explanation

The air in Earth's atmosphere is made up of approximately 78 percent nitrogen and 21 percent oxygen.