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.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

i think the answer is terrae but not 100 percent sure. ▓▬▬ §

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.