12. which one of the following chemical equations is balanced?

Achemistry student weighs out of phosphoric acid , a triprotic acid, into a volumetric flask and dilutes to the mark with distilled water. he plans to titrate the acid with solution. calculate the volume of solution the student will need to add to reach the final equivalence point. round your answer to significant digits.

The tilt of the earth's axis of rotation is responsible for the a) ocean's tides. b) size of the moon. c) brightness of stars. d) earth’s seasons.

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?