Khoa học

An inorganic compound (of molecular formula H₂O) found at room temperature and pressure as a clear liquid; it is present naturally as rain, and found in rivers, lakes and seas; its solid form is ice and its gaseous form is steam.

An affair, condition, or subject, especially one of concern or (especially when preceded by the) one that is problematic.

Electromagnetic radiation in the wavelength range visible to the human eye (about 400–750 nanometers): visible light.

A (usually self-sustaining) chemical reaction involving the bonding of oxygen with carbon or other fuel, with the production of heat and the presence of flame or smouldering.

The impetus behind all motion and all activity.

Ability to influence; strength or energy of body or mind; active power; vigour; might; capacity of exercising an influence or producing an effect.

Deoxidized.

A heavy, pliable, inelastic metal element, having a bright, bluish color, but easily tarnished; both malleable and ductile, though with little tenacity. It is easily fusible, forms alloys with other metals, and is an ingredient of solder and type metal. Atomic number 82.