Explanation

• The chemical formula for water is H₂O.

Atomic masses:

• Hydrogen (H) = 1 amu each → 2 × 1 = 2 amu
• Oxygen (O) = 16 amu

Total molecular mass = 2 (from H) + 16 (from O) = 18 amu.

Last verified on 07-06-2026

Explanation

• The law that states mass can neither be created nor destroyed is the Law of Conservation of Mass.
• This law states that mass remains constant in a chemical reaction.
• Matter cannot be created or destroyed, only transformed.

Last verified on 02-04-2026

Explanation

• Copper (تانبا) is a good conductor of electricity.
• It allows electric current to flow easily.

Additional information:

• Metals are generally good conductors.
• Non-metals usually do not conduct electricity.
• Good Conductors: Copper, Silver, Gold, Aluminum, Graphite
• Bad Conductors: Plastic, Rubber, Wood, Glass, Air

Last verified on 07-06-2026

Explanation

• The usual gases used for lifting airships are hydrogen and helium.
• Hydrogen is the lightest known gas and thus has great lifting capacity,
• Helium is not as buoyant but is far safer than hydrogen because it does not burn.

Last verified on 01-04-2026

Explanation

• The hardest substance in the world is diamond.
• Its hardness is due to the strong covalent bonding between its carbon atoms.
• This making it the most resistant to scratching.

Additional information:

• Category: Native minerals
• Cleavage: 111 (perfect in four directions)
• Crystal class: Hexoctahedral (m3m); H-M symbol: (4/m 3 2/m)
• Crystal habit: Octahedral
• Crystal system: Cubic
• Dana classification: 1.3.6.1
• Density: 3.5–3.53 g/cm3 3500–3530 kg/m3

Last verified on 07-06-2026