The concentration of arsenic (As) and selenium (Se) in a drinking water well were 2.0
and 3.8 ppb. (a) convert arsenic concentration into ppm and mg/L. (b) convert selenium concentration into molarity (M) and micro-molarity (um). (c)have the concentration exceed the maximum contaminant level (MCL) of 50 mg/L for both elements? The atomic weight of Se is 79.