Which of the following best describes alternating current? A. current that constantly turns on and off

B. current in which charges change direction

C. current that gains and loses electrons

D. current that increases and decreases in temperature

Asolution of naoh has a concentration of 25.00% by mass. what mass of naoh is present in 0.250 g of this solution? use the periodic table in the toolbar if needed. 0.0625 g what mass of naoh must be added to the solution to increase the concentration to 30.00% by mass? g