Explanation

• The first metal discovered and used by humans was Copper.
• It was found in native form (pure metal) in nature.
• Early humans used it for tools and ornaments before iron age.
• This period is known as the Copper Age (Chalcolithic Age).

Last verified on 30-05-2026

Explanation

• Atoms are made of subatomic particles: protons, neutrons, and electrons.
• Mass number represents the total number of heavy particles in nucleus.
• Only protons and neutrons contribute to atomic mass.

Last verified on 14-05-2026

Explanation

• The chemical name of chalk is Calcium carbonate.
• Its chemical formula is CaCO₃.
• It is a soft, white mineral.
• Commonly used in blackboard chalk and limestone.
• Found naturally in rocks and marine shells.

Last verified on 30-04-2026

Explanation

Bismuth is the only pure metal that expands when it solidifies (freezes).

Most substances contract on solidification, but bismuth behaves unusually—its solid form occupies a slightly larger volume than its liquid form.

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Explanation

• The cheapest source of electricity generation is Solar Energy.
• Solar energy uses sunlight, which is free and renewable.
• Costs have dropped significantly due to modern solar panel technology.
• It avoids fuel costs and environmental pollution.

Last verified on 31-03-2026

Explanation

• Copper is a chemical element with the symbol Cu and atomic number 29. 
• It is a soft, malleable, and ductile metal with a reddish-orange color.

The some major elements with their symbols:

• Hydrogen - H
• Sodium - Na
• Carbon - C
• Nitrogen - N
• Oxygen - O
• Fluorine - F
• Chlorine - Cl
• Potassium - K
• Helium - He
• Neon - Ne
• Calcium - Ca
• Sulphur - S
• Phosphorus - P
• Aluminium - Al
• Magnesium - Mg
• Iron - Fe

Last verified on 16-03-2026

Explanation

• The filament of an electric bulb is made of Tungsten.
• Because it has a very high melting point (~3422°C).
• It can glow brightly without melting.
• Tungsten provides efficient and long-lasting light in incandescent bulbs.

Last verified on 15-03-2026

Explanation

• A molecule is the smallest particle of a compound that retains the chemical properties of that compound.
• It is made up of two or more atoms chemically bonded together.
• Molecules can be elements (O₂, N₂) or compounds (H₂O, CO₂).

Last verified on 08-02-2026

Explanation

• An eraser is usually made of rubber, which does not attract magnets.
  • Magnetic materials are substances that are attracted by a magnet.
  • Materials like iron and steel are magnetic, while rubber or plastic items are non-magnetic.

Additional information:

• Common Magnetic Materials:
  • Iron
  • Nickel
  • Cobalt
  • Steel (paper clip, iron nail)
  • Some alloys
  Non-magnetic examples: Rubber, wood, plastic, paper.

Last verified on 07-03-2026

Explanation

• In solids, particles are tightly packed and cannot move freely.
• Their motion is limited to vibrations around fixed positions.
• Solids retain definite shape and volume due to limited particle motion.

Last verified on 07-03-2026