In a direct current, the electric charge, or current, only flows in one direction. In an alternating current, the electric charge changes periodically.
C, Since binary ionic compound is only of 2 elements. Mg is ionic and so i F so thats it. H20 is covalent B is more than 1 element, D looks dodgy, nah its dat ionic compunds wouldnt form big ones like SF (6)
Increase .... decrease .... presumably it's the "best shape" for a body which has been formed by the gravitational force
