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

Bakelite is an insulator.

Additional information:

• Developed: 1907 by Leo Baekeland (Belgium/USA)
• Heat resistance: up to 250°C
• Electrical resistivity: ~10¹⁴ Ω·cm
• Used in: electrical fittings, telephones, radios, automotive parts

Last verified on 17-01-2026

Explanation

• Tsunami is a series of large ocean waves caused by underwater earthquakes, volcanic eruptions, or landslides.
• The destruction caused by a tsunami is mainly related to its height when it reaches the shore.

Additional information:

• 2004 Indian Ocean Tsunami: up to 30 m in some areas
• 2011 Japan Tsunami: ~40 m wave recorded in Miyako
• Average tsunami wave in open ocean: <1 m
• Speed in deep ocean: 500–800 km/h

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

• Lactose is a disaccharide, made of glucose + galactose.
• Monosaccharides are the simplest sugars that cannot be hydrolyzed into simpler sugars.
• Examples include glucose, fructose, and glyceraldehyde.

Additional information:

• Glucose (C₆H₁₂O₆) – main energy source in cells
• Fructose (C₆H₁₂O₆) – found in fruits and honey
• Glyceraldehyde (C₃H₆O₃) – simplest monosaccharide (triose sugar)
• Ribose (C₅H₁₀O₅) – part of RNA and DNA
• Galactose (C₆H₁₂O₆) – combines with glucose to form lactose

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

Explanation

• Brass gets discoloured in air due to Hydrogen Sulphide (H₂S).
• This gas reacts with the copper in brass to form a dark layer of copper sulphide, giving it a tarnished appearance.

Additional information:

• Tarnishing is superficial and can be cleaned using polishing or chemical cleaners.
• This phenomenon is also called sulphide tarnishing.

Last verified on 17-01-2026

Explanation

Fruits generally have the maximum water content.

Additional information:

• Fruits: 80–95% water (e.g., watermelon 92%, orange 87%)
• Vegetables: 70–95% water (e.g., cucumber 96%, spinach 91%)
• Sauces: ~50–80% water depending on type
• Purpose: Hydration and nutrient supply

Last verified on 17-01-2026