Which compounds give one singlet in the 1h nmr spectrum? ch3ch3 1461113dichloro22dibromo 1461123dimethyl2butene ch3―c≡c―ch3 ch2═chch═ch2 14611cyclohexadione 14611cyclopentane 14611123tribromopropane 14611ketone 14611ester

1. they vary with a higher number because boiling is way hotter than melting

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.