Awater holding tank measures 105 m long, 40m wide, and 11m deep. traces of mercury have been found in the tank, with a concentration of 60mg/l. what is the total mass of mercury in the tank?

2772mg

To answer this question first you must know how much the water tank volume. The calculation would be:
Water tank V: 105m x 40m x 11m= 46200m3

After that, you need to convert the m3 into liter, then multiply it with mercury mass index. The calculation would be
Mercury mass: 46200m3 x 0.001 l/m3 x 60mg/l = 2772mg