Explanation

• Combustion is a chemical reaction in which a substance reacts rapidly with oxygen to produce heat and light.
• Commonly observed when wood, coal, or fuel burns.
• Combustion is an exothermic reaction because it releases energy.

Last verified on 10-03-2026

Explanation

• Antoine Lavoisier, a French chemist, is credited with discovering the law of conservation of mass in 1789 (1785).
• He demonstrated that matter cannot be created or destroyed in a chemical reaction, only transformed from one substance to another.

Last verified on 10-03-2026

Explanation

• Chlorofluorocarbons (CFCs) are chemical compounds used in refrigerators, air conditioners, and aerosol sprays.
• When released into the atmosphere, CFCs destroy the ozone layer by breaking down O₃ molecules.
• The ozone layer protects Earth from harmful ultraviolet (UV) radiation.

Last verified on 10-03-2026

Explanation

• Mitosis is the process by which a single cell divides to produce two identical daughter cells.
• It is essential for growth, tissue repair, and development in multicellular organisms.
• Mitosis maintains the same number of chromosomes in each new cell.

Additional information:

• Meiosis is different; it occurs in sex cells and reduces chromosome number by half.

Last verified on 10-03-2026

Explanation

• The stomach is an organ involved in digestion, not waste elimination.

1. Lungs: remove carbon dioxide through exhalation
2. Kidneys: filter waste and excess substances from the blood, producing urine
3. Skin: removes waste through sweating
4. Liver: detoxifies harmful substances and aids in their removal

Last verified on 10-03-2026

Explanation

• Car brakes are typically hydraulic systems, not pneumatic systems.

The examples of pneumatic systems:

• Spray gun: uses compressed air to atomize and spray paint or other materials.
• Bicycle pump: uses compressed air to inflate tires.
• Vacuum cleaner: uses compressed air to create suction and lift dust and debris.

Last verified on 09-03-2026

Explanation

• Pascal's Law states that the pressure applied to a fluid (liquid or gas) in a container is transmitted equally throughout the fluid and to the walls of the container, and that the pressure is the same in all directions at a given point in the fluid.
• This principle has numerous applications in engineering, physics, and everyday life.

Last verified on 09-03-2026

Explanation

• Reflex actions are rapid, automatic responses to stimuli that occur without the involvement of the brain.
• Instead, they are mediated by the spinal cord or peripheral nerves.

Last verified on 09-03-2026

Explanation

The structure of the brain is similar to the structure of a Walnut, with both having:

• A hard outer layer (cranium vs. shell)
• A wrinkled surface (brain's cerebral cortex vs. walnut's surface)
• A distinct left and right half (brain's hemispheres vs. walnut's halves)

Last verified on 09-03-2026

Explanation

• The nervous system is the body system that controls and coordinates the functions of all other organ systems.
• It allowing for integration and regulation of various bodily functions.
• It consists of the brain, spinal cord, nerves, and sensory organs.

Last verified on 09-03-2026