Why is gas collected over water not pure

What is the molar mass of the anhydrous compound? answer using four significant figures. 36.02 g/mol 120.15 g/mol 156.12 g/mol

Amedication is given at a dosage of 3.000 mg of medication per kg of body weight. if 0.1500 g of medication is given, then what was the patient's weight in pounds (lbs)? there are 453.59g in 1 lb.

Salt in oceans comes from and of rocks