A student examines a cell with organelles J, K, L, and M labeled. -
-K
-L
-M
Which labels correctly identify the organelles?
O J: mitochondrion; K: nucleus; L: cell membrane; M: vacuole
J: nucleus; K: cell membrane; L. vacuole; M: mitochondrion
O J: cell membrane; K: nucleus; L: mitochondrion; M: vacuole
J: nucleus; K: mitochondrion; L: vacuole; M: cell membrane

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.

the term hydride is commonly named after binary compounds that hydrogen forms with other elements of the periodic table. hydride compounds in general form with almost any element, except a few noble gases. the trends and properties vary according to the type of intermolecular force that bonds the elements together, the temperature, its molecular masses, and other components. hydrides are classified into three major groups, depending on what elements the hydrogen bonds to. the three major groups are covalent, ionic, and metallic hydrides. formally, hydride is known as the negative ion of a hydrogen, h-, also called a hydride ion. because of this negative charge, hydrides have reducing, or basic properties. its special characteristics will be further discussed.

explanation: