Corrosive substance due to their capabilities of dissolving greases, proteins or mineral deposits such as limescale inside water pipes. In chemical uses, high chemical reactivity is often desirable, as the rates of chemical reactions depend on the activity (effective concentration) of the reactive species. For instance, catalytic sulfuric acid is used in the alkylation process in an oil refinery: the activity of carbocations, the reactive intermediate, is higher with stronger acidity, and thus the reaction proceeds faster. Once used, corrosives are most often recycled or neutralized. However, there have been environmental problems with untreated corrosive effluents or accidental discharges. Corrosive substance A
Magic cube classes not enough to qualify for the next class. <br>The smallest normal simple magic cube is order 3. Minimum correct summations required = 3"m" + 4 Each of the 3"m" planar arrays must be a simple magic square. The 6 oblique squares are also simple magic. The smallest normal diagonal magic cube is order 5.<br> These squares were referred to as ‘Perfect’ by Gardner and others! At the same time he referred to Langman’s 1962 pandiagonal cube also as ‘Perfect’.<br> Christian Boyer and Walter Trump now consider this "and" the next two classes to be "Perfect". (See "Alternate Perfect" below).<br>A. H.