7. the outermost electrons of the element vanadium (atomic #23) are in which energy level of the atom? how do you know?

When writing an electron configuration in orbital form, you put the last noble gas configuration in front, for vanadium it's (Ar). The s-block is filled with its capacity of 2 electrons since vanadium is a regular transition metal. The first d subshell, 4d, puts electrons into the 3rd shell not the outer shell. So it has 2 valence electrons. The exceptions to this rule are chromium, molybdenum, copper, silver and gold, which put one of the s electrons into the d shell.

Efficiency is an action of doing something. for example when you take a test. good efficiency means you did well but bad effeciency or no effiency means you did bad.