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

• Diamond is a naturally occurring allotropic form of carbon.
  • Allotropy means a single element can exist in more than one form with different structures and properties.
  • It is extremely hard.
  • It has a high melting point.
  • It is widely used in jewelry and cutting tools.

Additional information:

• Graphite – soft, good conductor
• Fullerenes (C60) – spherical molecules
• Carbon nanotubes – tubular, high strength
• Amorphous carbon – coal, soot
• Lonsdaleite – hexagonal diamond

Last verified on 17-01-2026