To determine the percentage of water in a hydrated salt, a student heated a 1.2346 g sample of the salt for 30 minutes; when cooled to room temperature, the sample weighed 1.1857 g. after the sample was heated for an additional 10 minutes and again cooled to room temperature, the sample weighed 1.1632 g. which of the following should the student do next?
a. use the smallest mass value to calculate the percentage of water in the hydrated salt.
b. repeat the experiment with a new sample of the same mass and average the results.
c. repeat the experiment with a new sample that has a different mass.
d. reheat the sample until its mass is constant.
e. use the average of the mass values obtained after the two heatings to calculate the percentage of water in the hydrated salt.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

i just calculated it all out, and not including weekends, and all the different days off. as of this school year (2018-2019) students are spending 2198 hours in school this year