Which of the following are correct? electrons generally occupy the lowest energy orbital first. the c atom has two unpaired electrons. the he atom has two electrons that have parallel spin in its 1s orbital. the arrangement of the orbitals is the same in a multielectron atom and a single-electron atom. in the li atom, the 3s, 3p, and 3d orbitals have different energies. the he atom has one electron each in 1s and 2s orbitals.

Electrons generally occupy the lowest energy orbital first. The C atom has two unpaired electrons. In the Li atom, the 3s, 3p, and 3d orbitals have different energies.

Explanation:

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.