Chemical substance identity of benzene, until the correct structure was described by Friedrich August Kekulé. Likewise, the idea of stereoisomerism – that atoms have rigid three-dimensional structure and can thus form isomers that differ only in their three-dimensional arrangement – was another crucial step in understanding the concept of distinct chemical substances. For example, tartaric acid has three distinct isomers, a pair of diastereomers with one diastereomer forming two enantiomers. An element is a chemical substance made up of a particular kind of atom and hence cannot be broken down or transformed by a chemical reaction into a different element, though it
Nasik magic hypercube original definition of nasik.<br> A "nasik" magic cube would have 13 magic lines passing through each of its "m" cells. (This cube also contains 9"m" pandiagonal magic squares of order "m".)<br> A "nasik" magic tesseract would have 40 lines passing through each of its "m" cells.<br> And so on. In 1866 and 1878, Rev. A. H. Frost coined the term "Nasik" for the type of magic square we commonly call "pandiagonal" and often call "perfect". He then demonstrated the concept with an order-7 cube we now class as "pandiagonal", and an order-8 cube we class as "pantriagonal".<br> In another 1878