An empty crucible weighs 12.437 2 g and the same crucible containing a precipitate from a gravimetric analysis weighs 12.529 6 g. (a) Each mass has six significant digits. What is the mass of precipitate contained in the crucible and how many significant digits are in that mass?
(b) The manufacturer states that the balance has an uncertainty of ± 0.3 mg. Find the absolute and relative uncertainty of the mass of the precipitate and write the mass with a reasonable number of digits.

I know the answer of (a), but need (b) answer.

What is the molecular formula of a hydrocarbon with m+ = 166? (write the formula with no subscripts, e.g. c4h10.) what is the sum of rings and double bonds in this compound?

In a sample of oxygen gas at room temperature, the average kinetic energy of all the balls stays constant. which postulate of kinetic molecular theory best explains how this is possible? a. attractive forces between gas particles are negligible because the particles of an ideal gas are moving so quickly. b. collisions between gas particles are elastic; there is no net gain or loss of kinetic energy. c. gases consist of a large number of small particles, with a lot of space between the particles. d. gas particles are in constant, random motion, and higher kinetic energy means faster movement.

Ahypothesis must be testable and falsifiable to be considered scientific a. trueb. false