Which statement best summarizes the law of conservation of energy?
a) when work is done, energy is lost.
b) heat flows from a warm body to a cold body.
c) if energy disappears in one form, it must reappear in another.
d) the fewer the number of valence electrons, the better the insulator.

In a file-oriented information system, a work file stores relatively permanent data about an entity is created and saved for backup and recovery purposes stores records that contain day-to-day business and operational data is a temporary file created by an information system for a single task

People with high self-esteem: accept their strengths and weaknesses. believe that failed experiences are failures of their whole self. feel good about who they are only when they reach total success. need positive external experiences to counteract negative feelings that constantly plague them.

Description: write function lastfirst() that takes one argument—a list of strings of the format "lastname, firstname" —and returns a list consisting of two lists: (a) a list of all the last names (b) a list of all the first names