Explanation

• The human body contains about 65% oxygen by mass.
• Oxygen is the most abundant element in the human body.
• It is mainly present in water (H₂O) and organic compounds.
• It is essential for respiration and energy production.

Additional information:

• Carbon: ~18%
• Hydrogen: ~10%
• Nitrogen: ~3%
• Other elements: ~4% (calcium, phosphorus, etc.)

Last verified 09-06-2026

Explanation

When white light passes through a prism, it splits into 7 colors, forming a spectrum known as a rainbow:

1. Red
2. Orange
3. Yellow
4. Green
5. Blue
6. Indigo
7. Violet

The separation of visible light into its different colours is known as dispersion.

Last verified on 08-06-2026

Explanation

• Sublimation is the direct transition of a solid into a gas without passing through the liquid phase.

Additional information:

Some common sublimating substances:

• Dry ice (CO₂) – solid → gas
• Iodine crystals – solid → violet gas
• Camphor – solid → vapor
• Naphthalene (mothballs) – solid → gas
• Ammonium chloride – solid → gas

Last verified on 13-03-2026

Explanation

• Pressure in gases is due to the collision of gas molecules with the walls of the container.
• Gas molecules are in constant random motion.
• They continuously strike the container walls.
• These collisions create force per unit area (pressure).
• More collisions mean higher pressure.

Last verified on 08-06-2026

Explanation

• Photosynthesis produces glucose and oxygen.
• Green plants use sunlight, water, and carbon dioxide.
• This process occurs in chloroplasts using chlorophyll.
• Glucose is used as food for energy and growth.
• Oxygen is released as a byproduct into the atmosphere.

Last verified on 10-03-2026