Price Variance. Definition: Price variance is the actual unit cost of a purchased item, minus its standard cost, multiplied by the quantity of actual units purchased. The price variance formula is: (Actual cost incurred-standard cost) x Actual quantity of units purchased. = Price variance. If the actual cost incurred is lower than the standard cost, this is considered a favorable price variance.
Calcium occurs in water naturally. Seawater contains approximately 400 ppm calcium. One of the main reasons for the abundance of calcium in water is its natural occurrence in the earth's crust.
Magnesium occurs naturally only in combination with other elements, where it invariably has a +2 oxidation state. The free element (metal) can be produced artificially, and is highly reactive (though in the atmosphere, it is soon coated in a thin layer of oxide that partly inhibits reactivity â see passivation).