The 1H NMR spectrum of compound A (C15H14O) shows only two signals: a multiplet at 7.15 ppm and a singlet at 3.55 ppm in a 5:2 ratio. The IR spectrum has no absorption in the 3200–4000 cm–1 region, but strong peaks can be found near 1700 cm–1. Compound A reacts with NaBH4 followed by acidification to give compound B of the molecular formula C15H16O. The reaction of A with CH3MgBr, and then with H3O+, gives C, with a molecular formula of C16H18O. Suggest structures for B and C.

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.