The sodium ion may be abbreviated as Na+ or as simply Na. Sodium can occur as a salt in a crystalline solid. Sodium chloride (NaCl), sodium phosphate (Na2HPO4) and sodium bicarbonate (NaHCO3) are commonly occurring salts. These salts can be dissolved in water or in juices of various foods.
A Reference Point is something you use to determine the position of an object, but the reference point has to be something that doesn't move at all. For Example: A Tree. A Reference Point is something you use to determine the position of an object, but the reference point has to be something that doesn't move at all. For Example: A Tree.
focal point. noun. 1. Also called principal focus, focus. the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection. 2. a central point of attention or interest.