An electric motor is connected to a battery. the current flows through brushes to a commutator ring, which is attached to an electromagnet turning through a permanent magnetic field. what is the purpose of the commutator ring? a. it periodically reverses the current flow through the electromagnet. b. it turns the electromagnet in the opposite direction. c. it allows mechanical energy to be converted into electrical energy. d. it keeps the electromagnet from losing its magnetism.

Achemistry student needs to standardize a fresh solution of sodium hydroxide. he carefully weighs out of oxalic acid , a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in of distilled water. the student then titrates the oxalic acid solution with his sodium hydroxide solution. when the titration reaches the equivalence point, the student finds he has used of sodium hydroxide solution.calculate the molarity of the student's sodium hydroxide solution. be sure your answer has the correct number of significant digits.

Why can water dissolve many ionic compounds

If 15 drops of ethanol from a medicine dropper weigh 0.60g, how many drops does it takes from a dropper to dispense 1.0ml of ethanol? density of ethanol is ethanol is 0.80g/ml.