Acetylene (C₂H₂) is commonly used in oxy-acetylene welding and cutting due to its high flame temperature of about 3,300°C.

At -40°, both Celsius and Fahrenheit scales show the same value: -40°C = -40°F.

Carbon-14 has a half-life of approximately 5,730 years, making it useful for dating archaeological artifacts.

The electromagnetic spectrum in order of increasing frequency: Radio < Microwave < Infrared < Visible < Ultraviolet < X-ray < Gamma.

A plane mirror has infinite focal length because it does not converge or diverge light rays.

The Doppler effect causes the observed frequency to increase when a sound source moves towards the observer due to compression of sound waves.

The First Law of Thermodynamics is the Law of Conservation of Energy, which states that energy is neither created nor destroyed but only transformed.

Sound cannot propagate through vacuum because it requires a medium (solid, liquid, or gas) to travel. Sound travels fastest in solids, slower in liquids, and slowest in gases. Frequency determines pitch.

Fluorine has the highest electronegativity value (3.98) on the Pauling scale. Electronegativity is the tendency of an atom to attract electrons in a chemical bond. As we go from fluorine down the halogen group, electronegativity decreases.

Light and electrons exhibit wave-particle duality, meaning they behave as both waves and particles depending on the experiment.