If carbon dioxide gas is collected over water at 25 °C and 775 torr, what is the partial pressure of the CO2? The vapor pressure of water at 25 °C is 24 torr. OPTIONS:
A. 23.8 torr
B. 750 torr
C. 751 torr
D.775 torr

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.  

explanation:

a