Why are iron needles used in compasses

An atom of sodium-23 (atomic number = 11) has a positive charge of +1. give this information, how many electrons does it have? how many proteins and neutrons does this atom have

What does the symbol (–hfus) indicate in a phase change?

Scientists have developed an explanation of a phenomenon from several verified hypotheses. the explanation has been confirmed through numerous experimental tests.which option best describes this explanation? a. scientific lawb. research questionc. hypothesisd. scientific theory