Explanation

Metalloids have properties of both metals and non-metals.

They can conduct electricity better than non-metals but worse than metals.

Examples include silicon, boron, and germanium.

Metalloids are widely used in semiconductors and electronics.

Their mixed properties make them important in modern technology.

Explanation

Explanation

Helium is the rarest, as it's present in much smaller trace amounts (around 5.2 ppm)

Oxygen: ~209,000 ppm (20.9%)

Carbon Dioxide: ~420 ppm (0.04%)

Neon: ~18 ppm (0.0018%)

Helium: ~5.2 ppm (0.00052%) 

Xenon is generally considered the rarest of the common noble gases,

Explanation

• Sedimentary rocks are rocks formed by the deposition and compression of sediments over time.
• Also called stratified rocks because they are formed in layers (strata).
• Often porous, meaning they have small holes (pores) that can contain water or other fluids.

Additional information:

• Cover about 75% of the Earth's surface.
• Examples: Sandstone, Limestone, Shale.
• Usually softer and less dense than igneous rocks.

Explanation

• Limestone is a sedimentary rock.
• It is formed mainly from the skeletal fragments of marine organisms such as coral and shells.
• It is commonly used in cement, construction, and soil treatment.
• It is main component is Calcium carbonate (CaCO₃).

Last verified on 17-01-2026

Explanation

Butter and margarine are colloids.

They are specifically oil-in-water emulsions.

Additional information:

• Milk – fat in water (oil-in-water)
• Butter – fat in water (oil-in-water)
• Mayonnaise – oil-in-water emulsion
• Fog – liquid droplets in air (aerosol)
• Gelatin – solid in liquid (gel)

Last verified on 17-01-2026

Explanation

• Hemoglobin is a protein found in red blood cells that carries oxygen.
• It is soluble in water, allowing it to move easily in blood plasma.

Additional information:

• Hemoglobin molecular weight ≈ 64,500 Da
• Soluble in physiological saline (0.9% NaCl)
• Insoluble in benzene, chloroform, alcohol

Last verified on 17-01-2026

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

• Brine freezing is the oldest method of freezing food.
• It involves immersing food in a cold brine solution (saltwater) to lower temperature quickly.
• Used historically for meat, fish, and dairy preservation.

Additional information:

• Brine freezing works because saltwater freezes below 0°C, allowing faster heat transfer.

Last verified on 17-01-2026

Explanation

• Quartz has a chemical formula SiO₂ and forms hexagonal crystals.
• It is a common mineral made of silicon and oxygen.
• It is widely found in the Earth’s crust.
• It is used in glass-making, electronics (quartz crystals), and watches.
• It is hard and resistant to weathering.

Last verified on 17-01-2026