What is the concentration of an AlCl3 solution if 150 mL of the solution contains 350. mg of cr ion?

Idon’t know how to solve this question

Consider the following reaction at equilibrium. 2co2 (g) 2co (g) + o2 (g) h° = -514 kj le châtelier's principle predicts that the equilibrium partial pressure of co (g) can be maximized by carrying out the reaction a. at high temperature and high pressure b. at high temperature and low pressure c. at low temperature and low pressure d. at low temperature and high pressure e. in the presence of solid carbon

What prefix multiplier is appropriate for reporting a measurement of 5.57 ×10−5 m?